I played both for quite a while last weekend, and I’d have a tough time picking one over the other because both are great, but I’d give the nod to Deadpool by a hair.
The only reservation I’d have is with the hit and miss Stern quality control. The Deadpool I played is less than a year old, but already looks more generally worn than some of the other Stern games that have been there for several years (MUS, ST, IM, ACDC, MET, GOT, SM) and almost certainly have a lot more plays on them. Also, the Lil Deadpool figure was missing from the game (seems like a weak point in the game, as others have had issues) and the bottom GI was very dim.
The Maiden machine has been there about as long as DP and was likely built around the same time, but had no issues at all.
My favorite pleasant surprise that day was ACNC. It’s simply excellent in every way, Spooky should be very proud, and you guys waiting on one will be greatly rewarded for your patience!