.30 Calibers are my most prolific in my safe, in fact I'm a little to heavily invested in .308 calibers. I have .30 Carbine, .300 BO X2, .30-30 Win (lever, bolt action, and single shot) .300 Savage X2, .308 Win X2, .30-06, and .300 H&H.
.22 cals would be the next, especially if you count rimfires. .22lr X3, .22 WMR, and .223 Rem X5.
6mm caliber is the one I shoot the most. I have rifles in 6X45, 6X47 Rem, .243 Win, and 6mm Creedmoor X3. I'm thinking I'll probably add the GT soon.
Handguns 9mm wins for the one between the wife and I we have six pistols. However, she carries a .357 Mag LCR for her CC. My favorite to shoot is a Rem 1911R1 Carry Commander. I inherited from an older hunting buddy who passed along with his Ruger Deerfield Carbine in .44 Mag.
I shoot 12 ga Win 1300, and my wife shoots an 870 20 ga when we pull out shottys.