I've owned a number of 3DOs over the years. The 3DO library is a lot like the sega cd library. Lots of FMV based games which were cool at the time but might not be of interest to you unless you're nostalgic for that period. In fact there are many shared games between the platforms (but probably not the ones that you'd buy a sega CD to play). There are some other action type games that were quite good at the time including 3d games with early textured polygon graphics but about 95% of those games were all ported to the PS1 (ie: Need for Speed 1, Road Rash, Total Eclipse, Offworld Interceptor, Gex, Primal Rage). The prices have shot out of the roof with 3DO stuff, but you can theoretically burn games and play them if the disc drive still works (one 3do I had ran burned games just fine while another I had later on would glitch out when playing burned game, playing them with lots of stutters and stuff, probably bc of the age/condition of the old cdrom drive).
I think the system physically looks cool and I have nostalgia for that era, heck I've owned maybe 4 or 5 3dos over the years (including ones I bought that were broken), but if you have no attachment to the era or the system and you're just looking at it as a way to find interesting and potentially obscure games, you'd be much better off and save a lot of money going with something like a sega saturn, and/or going for a PS1 longbox collection (many of the graphically better 3do games were ported to and released in the early years of the PS1 back when sony was releasing games in longboxes).
Btw, cautionary note: there are some plastic gears in the cdrom drive for the 3DO FZ-1 and FZ-10 that become brittle and crack with age, even if the system is kept in its box for decades and not used, when the gears are cracked the cdrom drive appears to be dead. Expect that to be an issue with any 3do you pick up these days. It's apparently possible to 3d print replacement gears but I didn't have the means to do that myself. Also the 3do is a bitch to dissassemble, it takes a lot of time to dissassemble and reassemble compared to other systems.
So to answer your question... exploring the 3do library is like being limited to the PS1 games that came out in 1995 only. Overall, 3do games are graphically inferior to games designed for the PS1. There's a lot of "flash" in the games, such as having lots of FMV and CD audio which was novel at the time, but you're simply not going to find anything on the level of like, Crash Bandicoot or Ridge Racer or 3d fighting games like Tekken (or even Battle Arena Toshinden for that matter). And... most of the games released were done by American developers so think about how many early PS1 games you like that were designed by studios like EA and Crystal Dynamics and that's kinda what the feel of the system is like. You won't find neat Japanese flavored stuff like Jumping Flash. Ironically the 3do was semi popular in Japan and there's a huge library for the system there... however the Japan exclusives are overwhelmingly visual novel type stuff or interactive photo stuff or mahjohng titles, rather than awesome obscure Japan only arcade style games.
It is a sexy looking system though