I'll play! Not so much on hardline specifics like brand, but..
-concealed-hammer .357 snub, probably a S&W
Why: I don't own a revolver, I don't own any handgun stronger than 9mm. The snubbie is very practical for concealed carry. The .357 may well be overkill, but I won't object to having an 'overbuilt' .38!
-a 1911 in .45.
Why: I don't own one - in fact, I haven't even shot one, ever!
NUFF SAID?
-A .357/.38 SAA clone
Why: Again, I don't own one, though I have shot one in .22. A real piece of American firearm history. But I want the .357 caliber to match up with my snub.
-M1 Garand.
Why: Historic, and they're not getting any more plentiful.
Spot #5 isn't set in stone, but they have in common that I as a relative n00b have never owned any of them - and "I wannit!"
-S&W M&P TRR8 (or another 7 or 8 shooter revolver)
-AK-47
-S&W M&P snubbie (I'll see how I like the steel-framed .357 first I guess)
-Kel-Tec PF9
Uhhh...hmmmm. Guess that's about it, actually.