I say P90. I love mine, although it is getting supplanted by another .45 (gasp!). I have heard good and bad about the 345. The people that like it really, really seem to like it, the people that don't, well... Personally, I am a HUGE Ruger fan, and I don't care for the 345. When they first came out, I ran down to the store to look at one, and I wasn't impressed then and I am not impressed now. Keep in mind that this is just my opinion, but A: I thought they felt cheap. B: I thought the fit was icky. C: I didn't care for the layout. What I did like is that it is a fairly slim gun, and it was a handy size. The P90 is a big gun, but it is concealable (Weregunner got it right when he said it is harder to conceal. Harder does not mean "impossible"), and it is very, very rugged. I briefly contemplated selling mine after I got my new .45, and I just realized that I would really miss having it around. My new gun is neat and flashy and all of that, but my P90 has a ton of rounds through it, and I know I can depend on it. I figure that earns it the right to stay in my collection.