[epimetheus]

I use a 2013 MBPro and own a 2015 Mac Mini, but wanted something portable to play video games. I had all of the main requirements you had too, with the added requirement that it could power a 2k monitor on Fallout 4 at the highest setting.

The only thing I found that let me configure it online, and met the requirements (would have preferred more than 16GB of RAM though), was the HP Omen.

Edit: It comes with a 4k screen, which I downgraded to 1080p (Mostly used on monitor), but also wish it had a 2k downgrade option. Mac's Retina resolution is just about perfect, and not really a fan of 4k yet, also on a 15 inch screen it seems a waste.