Alive! for me, all the way! I love Alive 2, but the "live" portion just seems too short. I love the studio songs and all, I would have preferred a "Side 4" worth of material. I realize they didn't want to repeat songs from the first live album, but I'm sure they could have come up with another side of live tracks. Apparently, Take Me and Hooligan were recorded for the LP, but not used. I'm sure there were a few others, as well. By Alive 2, KISS had trimmed down on songs like "Black Diamond" and 100,000 years. The songs were shorter, etc.
There is no other "album experience" like the first Alive. Possibly my favorite record of all time.