I chose nvidia when I made the switch to linux probably 8 years ago. At the time AMD had not yet started their open source driver efforts. I haven't had any major complaints besides updates once giving a black screen. During most of that time AMD drivers were making a lot of changes that I didn't want to deal with. I believe they are a good choice now but they certainly did not seem to be then.
As far as steam, I've been using it happily on mint the entire time. It has had a big picture mode for some time. I'm a little baffled by people who seem to be waiting for a steamOS general release to make the switch.
I switched to AMD after the RX480 and haven't looked back. That was 8 years ago, so there hasn't been a good reason to use NVIDIA for a long time.
It's fine if you want to use Mint, but it doesn't make Nvidia a good person here.