How good is a speedrun controller? Are there any players in the top 10 playing on the controller?

depends on what youre comfertable with, if youre more comfortable with controller than go controller, if youre more comfertable with kleybord than use keyboard

what do you classify as a 'speedrun controller'? i recently picked up an 8bitdo pro 2 wired to try speedrunning. the dpad is absolutely awesome and back paddles are cool too.

It's mostly preference, in some games it's easier to do movement with controller or maybe some slight advantages (e.g rw fastroll) due to the analog stick having 360 rotation and keyboard having only 0, 45, 90, 135, 180, 225, 270 and 315, which can be an advantage, but i prefer keyboard since it's "faster" for me since it's tap/hold not move and the 360 rotation isn't even that useful if at all for most games.

if none of this made any since don't worry too much it's mainly preference and what you're used to e.g if you did your play through with keyboard it's probably not worth learning the game on controller for speed runs and the opposite is true as well, might be a bit easier for some people to do keyboard due to how to controls work, but up to you.

There are top runners using either of them. Keyboard has a slight advantage for some tech but overall it's minimal difference. Just go with what you're comfortable with.