I've had MET Premium, KISS LE, Maiden Pro and now AC/DC Luci.
Of them all, I'd rank them...
I wanted to throw AC/DC off a cliff day 1, but then I realized I was just "spoiled" with Maiden. AC/DC is tough and just so much fun. Makes you a better player.
Maiden is a super forgiving shooter. Every game was a good length and I'd get pretty far, but all games started to be the same. If you like shooting loops, Maiden is the best. Code is excellent for it as well.
Met is a notch above. There's a lot more ways to attack the machine, then for CIU modes, you have to play the way the machine tells you. (Still there is a lot of bashing to get to CIU modes).
Kiss. Ah, I love Kiss the band. Have my tix for this summer. The game shoots ok (Aerosmith copy) but there are some things that bug me. The scoop is WAY too tight (cliffy makes it worse too). The Demon lock sucks when it malfunctions. Just a big pain which for me would work sometimes and sometimes wouldn't. Overall, I don't think Kiss is all that interesting to play though. It's cool that wizard modes are all achievable with the new code. I reached them all several times. Maybe that's when it really lost its appeal. The new code REALLY made it easier for me and I didn't necessarily want that.