My favorite pistol of all-time has got to be the M1911, hands down. There's just something about it.
As for rifles, I've always been partial to something chambered in 7.62mm:
It also doesn't hurt that I can field strip it and reassemble it with my eyes closed and can perform the entire manual of arms with it.
I wish I had the money right now to begin amassing an arsenal. Alas, I am but a poor college student.