It really depends on what they are out of.
The 8.8 rear and a Dana 44 are really about a toss up, so I'd say its a draw there.
The front, like I said, it depends...
Some are too narrow to really be effectly used in your ZJ. Others, are too wide. To some extent spacers can be used to correct this (for narrow axles, not the wide truck ones).
Some have weak factory knuckles, but they can be converted.
Some have small axle tubes and I'd really stay away from those. Being you say their older, you should be fine here.
All this being said, the 44 front will have definate advantages over a 30.
Basically, let me know what they are out of and I'll hook you up with the 411. If you don't mind me asking, how much is he looking at for them? That makes a difference too.