Apple

Blender and games run great on my M1 MacBook Air which doesn't get hot even with no cooling at all except via the external case and I mostly play games on the couch with the laptop on my lap.

After two or three hours with all 8 CPU cores and the GPU both pegged under 100% load, I can notice the heat on my bare skin but it's not uncomfortable. And it only does that in games - Blender gives the CPU/GPU enough of a break between renders to keep it cool.

The MacBook Pro, which does have a fan, is definitely not going to get hot. Forget about that issue. The fan will make it run cooler, and also faster since the CPU won't be thermally throttled (my M1 is permanently thermally throttled while playing games... still fast enough to get good framerates at moderately high graphics settings though);.

Just buy the most expensive one you can afford. You're going to love it. The only thing to be aware of is external display support, which isn't very good on the low end models... but the M3 MacBook Air has improved that significantly and Apple has said there will be a firmware update to the M3 MacBook Pro soon to do the same thing.

I have a 16-inch M3 but really don’t expect you would see any difference in power and thermals on the 14-inch. I can’t directly compare, but I’d run out and bought a 14-inch M2 at Costco shortly before the M3 was unveiled. It wasn’t quite the specs I wanted but it was on sale and I’d picked up a contract where I quickly realized I needed an upgrade from my 2015 Air. It soon became apparent that the 512 GB SSD would get too full too fast, so I switched to a 16-inch M3. They really felt largely identical and I didn’t notice any difference in heat between either.

I would go with the largest internal storage you can buy, since that can’t really be upgraded later. If you prefer the smaller size that’s a bonus; it’s certainly more portable.

I don’t believe heat to be a significant issue with the 14 inch device. I am a fan of the smaller form factor and were I to buy one today, I would select the m3 max chip with the 14 inch form factor, but I am selecting it for the gpu cores. If you don’t plan on needing those, the m3 pro is a good chip.