I currently own all three of these games. I’ve owned Iron Man and ST each since 2014 and have had TNA for a few months. All three are great games.
To be clear: ST is objectively an easy game and it does not fight you...the shots flow from one to another, both ramps are wide open and there is a not a single shot that puts the ball in much jeopardy if it is missed other than (maybe) the warp ramp. The left ramp is one of the easiest back hands in pinball and the left orbit is also an easy backhand. The magnet, such as it is, doesn’t really “fling” the ball at you due to its location being behind the drop target.
Iron Man is an awesome game, it’s the only game I’ve bought NIB twice, but it substantially shares a layout with Austin Powers, Metallica, and GotG (all Borg games with materially the same shots). This isn’t a big deal unless you have two of those four games side by side...
TNA is a scrappy fighter but it shines in multiplayer action. If you have friends over who play with you go for a TNA. If you play by yourself mostly go for one of the other two...that’s my advice as an owner of all three. TNA is my favorite of the three.