me and my friend are interested in speedrunning a co-op game. what are the best co-op runs?

On what platform?

PC

Minecraft co-op runs look to be popular.

I also have an xbox 360 available

You can also try running any LEGO games on co-op mode

These are the ones I've done in the past with my brother, highly recommend them!

Syndicate (2012): https://www.speedrun.com/syndicate2012 The Adventures of Cookie & Cream: https://www.speedrun.com/the_adventures_of_cookie_and_cream (While it's PS2/PS3, you can use emulator) Never Alone: https://www.speedrun.com/neveralone

RIght now 3 main co-op games are of interest to me

Monaco: What's Yours is Mine (semi-stealth heist game) The Escapists 2 (Sandbox style Prison Escape Game) Lovers in a Dangerous Spacetime (Kind of a shoot em up, but with a ship controlled by platforming around to pull levers/turrets on the inside)

I also really love Overcooked 2 and Moving Out but woudn't speedrun them due to how their timers work and most of the speedrun just making sure to beat all the levels on the first try.

Factorio any% duo: https://www.speedrun.com/factorio#Any_Duo

Go try astroneer coop runs. :)

Streets Of Rage 4 has co-op categories :)

Don't forget portal 2 coop, great game, decent speedrun.