Any good coop games?

Since you liked Left for Dead, how about Warhammer: Vermintide, Payday 2, Killing Floor and Dying Light
For non FPS I recommend Assault Android Cactus

Zombie Army Trilogy is good.

ghost recon wildlands and breakpoint, division 1&2.

Overcooked! 2
Ultimate Chicken Horse

Be a farmer in stardew valley coop buddy. Not like your classic FPS games.

If you're interested in quick multiplayer-fun:
Speedrunners
Overcooked
Stick Fight
Battleblock Theatre
Rayman (the last two...but I think you need to be on the same PC for these)
Don't Starve Together (for having a more complex game in the list)

Unloved, unrailed, the mod for half life 2 (synergy), the mod Caveblazers together, golf with friends, castle crashers

elder scrolls online
sniper elite 4
hunt showdown(3players)

I mostly play co-op/multiplayer games with friends haha.
Here are some:

Deep Rock Galactic
Trine series
Terraria
Starbound
Stardew Valley
Overwatch
Borderlands series
Monster Hunter: World
Moon Hunters
Human Fall Flat
Killing Floor 1 and 2
Age of Empires/Mythology (vs - also be prepared for lots of teaming up/backstabbing and games that can take forever. Fun though hah)

Shank
Some how I missed first line, NVM

Spelunky
Enter the Gungeon
Portal 2