I can currently load 16 calibres. Nearly all with a single stage rockchucker. I also use an RCBS turret press for when I do two consecutive actions, e.g decap and flare, or seat and crimp.
Most loaded calibre by number is .32 S&W Long (11K+) for my Walther GSP, most by weight of lead is .45 ACP (170 lbs), most by total powder weight is .45-70, although that is black powder.
Other calibres I load and shoot at least annually are .223, .308, .303 Brit, .303 Savage, .300 Savage, 6.5x55, .38 Special, .357 Mag, .44 Mag, .577-450 Martini-Henry, 12.7x44R, and even some 9mm.
In learning what to do and what not to do, I have had a few fizzles and exactly 3 squib loads that stuck the bullet in the pistol barrel.
I actually shoot more .22 LR than anything else, however - I go through a couple of cases per year.