I use OpenWRT and I love the ability to tightly control my network. It also has very good performance.
With that being said, if you don't have a good familiarity with Linux and Networking it could be a struggle for the more advanced functionally. If you're just a average home user you can flash it and then go to wireless and create a new wireless network. Luci shows network hardware that's available to it so you may need to look up which one is the 5Ghz band and which one is the 2.5 GHz band.
Another thing, make sure you get on the OpenWRT security mailing list. Its fairly rare for a security issue to affect OpenWRT but when it does it will require a manual update. If you want to upgrade your device to the latest update that also is a manual process.