I'm not a huge fan of either theme... and I got sick of looking at plastic toy action figures mounted on the IM playfield... but I really like the game play IM offers. Tron is slightly better to look at, but the game has never really done much for me.
I like IM better (happily owned it for nearly 2 years), but ultimately could do without the way the IM theming was executed.
Rai... I'm guessing you're trying to figure out which one you'll eventually sell?