it makes sense to keep what you like and use, and get rid of what you don't. I'm a 3 gun competition, shoot steel, USPSA, carry, keep for the house, etc.
My goals are to get down to 22lr, 9mm, 45, 223, 12 gauge.
but I already have an LCP in 380 that I carry, a 38 my wife keeps in the car, etc. but I don't have to have lots of ammo for those. I'm down to 1911s and M&Ps for games and carry, since the grip angles are the same and the mags all work in each gun. in 223 I'm running all AR stuff. not because it's the best, but it's what I have and I'm familiar with it. Shotguns, I like an 870 but you may like a 20 gauge better.
I think the best thing to do is decide what you are going to accomplish, and then work back from there. If my collection was destroyed and I was starting from scratch, I would do get:
STI 2011 9mm- competition, HD, practice
Les Baer TRS- perfect 45 in my book
S&W shield or XDs 9mm. Small carry gun
SBR AR for HD and zombies, range fun. practice with a 22 conversion kit
Game AR 18" 223 for matches and hunting
semi auto shotgun
but I have a couple of heirloom things, and guns I'm tied to, and random crap. I'm not sure I could get much lower than I'm at now.