A lot of people disagree with me on this, but I think the Halo CE remaster was done really well. It genuinely looked like a current gen (current being the 360, I mean) game, and being able to push a button and switch back to the old style was dope. The multiplayer being stripped out and turned into a Reach map pack was a real pisser, though. And the MCC is really good, even if there's some minor annoyances around the edges. (like no credits) Playing those games at 60 is a complete revelation.
Also, the remasters/remakes that Christian Whitehead and Stealth did of Sonic 1, 2, and CD are fucking superb. Technically cheating, but fuck it. Playing those games in 16:9 is absolutely incredible, and it is baffling that they've never brought 1 and 2 to consoles and PC. There's a reason they got to make Sonic Mania.