I would have to say it would be my perdersoli bp sxs 10 gauge, its light weight and I love experimenting with different loads from bird shot to patched roundballs.
I have only shot a small amount of guns but in my collection it would have to be my h&k USP. I just picked up an ar but haven't fired it yet. All these comments on 1911's makes me want to test one out!
Sig P226 9mm - favorite pistol (only pistol I own)
Beretta A303 12 ga. - favorite shotgun (only shotgun I own)
Tikka T3 Whitetail .270 Win. - favorite rifle (one last time, only rifle I own)
There you go, two good hunting guns, one good self-defense gun. No .22's (sold 'em to pay bills), no other pistols (sold 'em to buy the Sig), but I'm happy with what I have (although at some point would like an AR, maybe an over/under too, those would be last 2 guns I probably buy though).