Have both, if one had to leave it would be Demo Man, but only because I like the theme on T3 more (I do thoroughly enjoy the Demolition Man film, but think the theme wasn't very well integrated on the pin).

Both are very good bang-for-the-buck pins. Demo Man feels very unique, especially when played with the handles. The only widebody that isn't covered in contraptions that doesn't feel like it plays like a widebody (typically slower than a standard pin).

T3 is special amongst Sterns in that it is the only one that has a backbox game (that is actually pretty cool) and uses individual lights for the translite like older games. It is also all metal as far as ramps go and feels much more solid and more B/W-like in build nature.

Nope. Grew up playing T2 in the arcades and T2 is my favorite movie of all time, but I vastly prefer T3 to T2. Only thing T2 has over T3 is a MUCH better artwork package.