jag is alright. i never had one when it was new, or even played one for that matter. just got one recently and...well you definitely have to have an appreciation for what goes into making a videogame to find some enjoyment with these. basically as was said, every game feels very unpolished, unfinished, or just vastly lacking in quality when compared to the more mainstream consoles.
many games suffer from really low frame rates, which is i think the biggest turn off. some games like tempest and rayman are excellent. some, like checkered flag, are not. i actually really like cybermorph and would love to try battlemorph but i dont have a cd.
i got a 3do at the same time and...its terrible. i dont know if its just my console or all 3dos (i could never get a straight answer out of anyone) but they exhibit some serious interlace flicker. the screen practically jumps up and down its so bad, and ive tried it on multiple tvs. it actually looks better on an lcd hdtv simply because it cant flicker. the games more often than not suffer from poor framerates (15-20fps) and nearly every game worth playing has been ported to saturn or ps1. many games have that multimedia cd-rom feel, or just an unfinished unpolished one.
while the jag has a few "true classics" (rayman, tempest, avp...though the first two are on saturn and psx) the 3do's library is largely forgettable.
theyre both neat systems to try out but you might tire of them quickly. i really kinda regret getting them as it was quite a bit of money that couldve been used more productively. and i already have a saturn and ps1. i just didnt know so many of the games were just not worth it. the flicker of the 3do just kills it (gives me a headace), and the low framerates of most jag games kill them too.
i briefly compared tempest 2000 on jag and saturn and if you dont play one, you wont be able to tell what youre missing. i think the saturn has some scoring bugs or differences, the star field patterns seem to be different, and the shading/coloring on the playfield is a little different (jag actually looks better.) the saturn one has a better framerate.