I bought these two NIB.
XMLE when it was new and Tron a few months later when it was re-run by Stern.
At first, I was disappointed with XMLE, and would have said hands down Tron was the better game BY FAR!!.
I still think, all in all Tron is the better game, but mostly I would say that is due to the better code. Tron's code has been really polished to a great result. It's callouts and sound effects are as good as any pinball machine ever. It's super fun and fast. In fact I was so happy with the prior code I never upgraded until just now because I wanted to enjoy the new code as something new to savor. The prior code was really sharp, the new code just made it better, more polished or improved on what was already great.
I didn't like XMLE at all, I was about to sell it, but I began to play it to get it out of my system or to see if I wanted to sell it or not. And boy did this game grow on me. It was my least favorite pin, but now it's on the top-4. I really would have to say it's only let down by some unresolved code or maybe some poor callouts etc.. Code is not bad at all, but I'm only sad because I was hoping for one final brush up. It just seems to be missing that last final once over to the code that could have made it one of the better games.
I really like the spinning magnet (on XM), love the Night crawler toy, like the moving ramp. It has a few really interesting modes such as Gambit hurry up, and really shines in the amount of things to do, 8 hero modes (if you count NC and Gambit as such), has many different Villains to battle and has two wizard modes four multi ball modes. The machine itself which has more stuff than Tron and more things to do. But it's sad that it has almost great code while Tron is totally great.
To sum up:
XMLE more stuff to do, more shots, more toys, more code. But slightly let down buy the code which is 80% there but not exactly where I'd hope.
Tron, Less stuff to do, less shots, less code. But overall just fantastic in every regard. Much like IM which I really love as well, maybe not the most shots or the most amount of code or rules, but working within a short rule tree it manages to be magical.
Tron and IM really kind of short and not a lot of toys, but makes up for it by being super fun. XMLE more of a longer journey to get through a lot of modes.
I have 7 games, like them all very much.
At this time: Tron and IM tied for first place followed immediately by XMLE and AcDc premium or AcDc premium and XMLE in some order but not much difference to me.