Linux

My tip would be to make sure of your storage partitioning: Keep all your data entirely separate from system stuff then you can swap out distros pretty much as and when you please. Also: Debian stable, then testing when you're comfortable

I'm very particular to Fedora based distros, mainly because they sort of just work and keep at the cutting edge of the spectrum with little to no headaches.

If you want to go immutable, Bazzite is pretty solid for gaming, so is Kinoite.

But I can also recommend some Ubuntu/Debian based distros, as they are easy to maintain. PopOS and Linux mint are very good options as well. I would also suggest staying away from Ubuntu itself.

I've tried some arch based distros over the years, but end up dropping them because I find them unnecessarily convoluted to maintain and troubleshoot, but that's just me.

I have heard that Nobara Linux is great for gaming but I can not confirm since I use Arch btw

Use Debian.

Manjaro has had major package policy issues in the past. Trying to bash arch into a stable release cadence doesn't fucking work. Don't know how true this is today, but it was a pain a couple years ago when I rolled it.

My best luck with proper Linux development was on Debian and it's derivatives. If you don't need bleeding edge shite, it's great.

If you want something more up to date, debian based stuff like Ubuntu and Mint work well

You can check my post history but I'm a dev who also play and had no problem with Linux for years. I don't play emulation (which is cool, even have a RPi with arcade joystick) but modern games (Elden Ring, Baldur's Gate 3, Ruiner, and some indies) including VR (Half-life: Alyx, Virtual virtual reality, Eye of the template, Cubism, etc) both on desktop and on the SteamDeck. Well it's been few years and I can tell you the tinker to play ratio is easily 99.9% in favor of playing. I don't tinker with drivers or anything of the sort (unless I have to work with CUDA, but still then no problem) but it's true that before buying a game I check ProtonDB to insure it will actually work.

Now in terms of distribution I'm not sure it matters much, what I would though highly recommend is that you make few extra partitions, at least /home this way if you do decide to format (because you somehow broke the OS, want to hop distros, etc) then you will keep you data without having to copy anything on another drive or even slower through the network. It makes changing a breeze.

PS: IMHO as a dev do tinker as much as you need, it's the best way to learn and see which distro is actually the best for you, just backup your data first then you can go "crazy", enjoy it's definitely worth it, even more so as a dev who can at any time say "Oh... that part sucks, I can change it", it's literally liberating.

Manjaro is a fine distro and it could work well for you however it's based on Arch and the problem with Arch-based stuff for beginners is that there's a lot of stuff about it online and some of it is wrong. It's fairly easy to break your system by following random advice if you don't know any better. It doesn't help that Manjaro has some important differences from Arch and following advice meant for Arch can sometimes break it.

So if I were you I'd stick with the usual beginner recommendations like Mint or PopOS.

If you like Ubuntu I can only recommend Debian with KDE desktop (don't install the default gnome DE).

I just switched recently and it's a very clean feeling. No snap and no nonsens. Just stable and trustworthy.

I'm not familiar with OpenSUSE or Manjaro, but if you are familiar with Ubuntu, then I would recommend either Linux Mint or Pop OS. Both are Ubuntu-based, and Pop OS has a Desktop Environment that is very similar to macOS. Pop OS is also suited for gaming with Steam, but then again, I think Steam works well on any Linux distro. The team behind Pop OS is currently doing some major revamps to the OS, but these changes are not yet released for stable use.

If you are building a new machine, I highly recommend you check to see if your HW will be compatible with Linux. You might want to pay close attention to the GPU and Wifi card. NVIDIA requires special drivers to work with Linux, while AMD works out of the box. As for the Wifi cards, depending on the wifi drivers that are installed in the distro, you may have to tinker a bit to get that to work. I recommend having the option to use Ethernet at the time you are setting up the distro, just so you have internet access to download what you need.

The only thing to be careful with about building a brand new computer is sometimes the linux kernel takes a little while to catch up and support the latest hardware for some things. So maybe if any components you're planning to use are very new, look them up and see if they are supported yet.
As for a distro I always recommend Mint. Your plan to try out a bunch of them on a VM is a great idea.

If buying a graphics card is in your plans, but AMD. Nvidia does better cards, but AMD works with less bugs on Linux. I just switched and I'm quite happy with the results.

For distro, Mint is a safe bet.

I have seen a lot of people say they moved from Manjaro to Endeavour (including myself), but I don't think the two are trying to solve the same thing. Manjaro wanted to create a more stable version of arch (and had some shortcomings that ended up being deal breakers for many people), but endeavour just wants to be a more convenient way to install arch.

I would recommend Fedora, Debian, or Mint. I've also heard good things about OpenSUSE.

Also, alternative to running in a VM, put ventoy on a USB drive, then drop isos for all distros on it, and live boot them one after the other to see how you like them.

Pop OS, Linux Mint, Debian, Ubuntu

Even though I don't typically recommend an immutable distro to people with minimal Linux experience, as a dev and a gamer I've been pretty happy with the various uBlue images. Bluefin is a great out of the box image for devs and the uBlue images have a lot of compatability improvements over the Fedora ostree image their based off of. Bazzite is another good one specifically built for gaming.

Anything you pick, make sure to first do a web search on how well your games work on Linux.

I haven't had problems playing games like Skyrim, The Witcher 3, Stardew Valley, Minecraft, Terraria, Portal, etc on Manjaro GNOME.

If you'll be gaming I highly recommend one of the distros that use Gamescope like ChimeraOS or Bazzite. Probably Bazzite.

I use OpenSuse for gaming. A great distro.Highly recommend. An up to date kernel, stable and just works.

Had bad experiences with Manjaro so personally wouldn't recommend.

To me, a distro doesn't really matter (unless you're gonna be gaming), as long as you pick one of the popular ones. It's the desktop environment that you'll need to choose. My only advice to you is to go full red with your new PC, AMD all the way. That way, you won't need to mess with drivers or any of Nvidia's shenanigans. Everything is baked into the kernel and is plug and play. I write software, too, and I use Endeavour OS, and have been for the last 2.5 years. Not suggesting that you use it (this is something you'll have to conclude for yourself), but this is what I use and I love it. For gaming, I'd pick a distro that ships new packages (rolling release), so you're always caught up on the latest improvements for gaming on Linux. We also have distros that are fully dedicated for gaming, like Nobara, Bazzite.... Etc.

The OS on the Steam Deck is Arch based, just like Manjaro, so I imagine it'll do games.

I'm a fullstack developer as well, and use Arch as my daily driver, and have for the past 9 years. While I can't speak for Manjaro directly, just the upstream, I have some coworkers that use it without issue. I think it'd be fine for your needs, at least worth trying out. I hear a lot of bleeding edge horror stories thrown around but in that 9 years 95% of problems were of my own doing, and the 5% were easily fixed with a rollback of a package. Out of that, my downtime isn't worth mentioning it's so negligible. I feel my coworkers on macos have more issues with major version upgrades by far.

On Arch-based distros, pkgbuild is a great way to handle custom packages when needed, and the AUR is gives me almost everything I need that isn't in the official repos. It's a great developer environment.

I'm very interested in OpenSUSE Tumbleweed as well, was thinking of trying it out as my next distro on a personal machine to try out something new since I've been on a single distro for so long, but not because I need anything new, just sounds like fun.

OpenSuse is a good choice as long as you don’t need nvidia optimus support or anything for weird hardware

I always hear amazing things about opensuse. I didn't like it but I didn't have any issue with it. Just preferred fedora over it. I'd say give it a shot

Nowadays distro doesn't really matter. Just pick something that clicks with you. Almost everything is a flatpak now so it'll install on any distro. If you come across something only packaged for Ubuntu or Debian you can use distrobox.

Debian is pretty good for me. Before I used Debian I ran gentoo from scratch (idk what the newfangled name for that is, but the one where you compile everything). Before that I ran Slackware and before that I ran red hat in like 98-2002.

Set aside some cash for four or five big drives and make your old pc a nas.

You can have it operate as a Time Machine target for your Macs.

I’ve had Manjaro, and OpenSUSE recommended to me by a friend who likes both of them but he doesn’t game much and doesn’t need various software development tools.

If your friend is familiar around Linux, then I'd advice you to just stick to the distro they're using themselves. That's probably the best course of action.