I also recommend The Finals! It's exclusively multiplayer, and the only "grind" one needs to worry about is unlocking all the weapons and gadgets; it doesn't take long to do, and you don't even need all of them if you aren't going to use them. But there's nothing to level up or upgrade, so once you buy an item, it's just a permanent part of your kit. There's no story or campaign that you have to progress, no cutscenes to sit through. You just launch the game, pick a mode, and queue for a match.

I have like 750+ in-match hours logged, and have no plans on stopping.