To answer your question without pushing my favorite game off on you: Iron Man!
Unless you're a good player, it's more than deep enough to kick your ass over and over. If you ever complete Do or Die multiball, you'll be in the company of the greats of Pinball. It's immersive, with outstanding sound (get a Polk subwoofer to go with it). Also, you can stack two different multiballs, not just one. Obviously, start War Machine and bring in Whiplash. The second is a lot harder, but I accidentally did it last time I played my IM. You get War Machine ready and bring up Monger. Then, just before starting Monger multiball, slide a shot just to the left into War Machine and get ready for action. The next shot or two of War Machine multiball will inevitably start Monger multiball. It's very satisfying to do this, but extremely difficult. Rare to get extra balls on IM, as you can't earn one. You can adjust replay settings though and do it that way.
You can approach the game and modes any way you want and in any order, rather than feel like you have to play through a funnel. I generally flail on my first ball, aiming for the ramps and hoping to get lots of drones, IM standups, ramps, and Whiplash shots, but not enough to start anything. Then, second ball, I try to start them all to sneak into a very rare Do or Die wizard.
Oh yeah, set Monger to difficult so that he'll only come up from a straight up the middle shot once ready. Otherwise he's in your face too much.
IM isn't very deep, but it's deep enough for me, in fact, that rare magical single ball can get you to a wizard. More often though, you'll have to hit the start button a bunch.
Good luck with your decision!
