A title I've always wanted to play is DEZAEMON...

Basically, you get to make your own shooter! Yep -- draw your own sprites and backgrounds, or edit preexisting ones, all on your Saturn! The graphics are about SNES-/Genesis-quality. Unfortunately, only released in Japan (and, you know, Sony and Nintendo both are guilty of leaving some awesome shit in Japan -- but Sega takes the fucking cake. 90% of the saturn's best titles were Japan-exclusives, and the Dreamcast
still had awesome new games coming out in Japan until 2006. Sega of America is just fucking retarded, period. The 32X? ... The Saturn release where they didn't, y'know,
tell anybody? Seriously. And they continue to release HORRIBLE Sonic games. Anyway... ranting aside... I am going to have to buy me a Japanese Saturn, since it seems like
the shooter system. That reminds me: Did
any shooters come out for the American Saturn? Actually, did the American Saturn have ANY noteworthy titles, beyond Burning Rangers, Virtual On, and NiGHTS?! ANYWAY..........
my # 1 pick is...

uh-oh

looks like it's a TIE!
...yep, a tie between Einhander (psx) and Ikaruga (arcade/dreamcast/gamecube). Sorry!
It's like this: I've played Ikaruga more than any other shooter ever; it's wickedly addictive, and I'm a HUGE Treasure fan. At the same time, I feel like... I haven't played Radiant Silvergun (which it is a semi sequel to), so maybe I wouldn't be so blown away if I had Silvergun in my life.
Also, Einhander is simply unique as hell -- maybe the most unique and fun shooter ever -- and is often still overlooked, despite (or perhaps, because of) being publised by Square. You get to shoot gigantic mechs and steal their swords and rocket launchers and attach them to you... and you get to blow up everything, including buildings and big signs, all to the sounds of weird opera music and truly twisted, bizarre electronic sounds.
So, it's a tough call. I think Einhander is the better game, by far, but I think Ikaruga is my personal favorite.
Hope you enjoyed! And since I got this Dreamcast almost exclusively to play more shoot em ups... haha, it's so funny, people were like "OH MAN! SONIC ADVENTURE! SOUL CALIBUR!" Fuck that shit. First thing I did was buy Chu Chu Rockets and SeaMan and then I downloaded a shit ton of shoot em ups.