Just happened across this thread kind of late. I'll take..
1. Big Guns. There is a LITTLE more to it then the other 2 as far as objectives. I would rate "Fire" about here too. Mine is brutally fast with a CPR playfield.
2. Road Kings. Recently got one. Like the theme mostly. Pretty cool game play.
3. Millionaire. It was a decent game. Not looking too hard to replace the one I sold.