.22 cal

Jeep here!

Love shooting .22 cal.

Sold all my .177 guns...

Funny. I was going to say Jeep as well. 
Anyway. Like most have said. .22 is just easy to come buy. Even locally. I have no issues shooting crosman pellets from my airguns. Sure, they are not the same as H&N or JSB, or other brands but they do fine for the most part. Actually I have been rather impressed with crosmans .177 10 grains in my Leshy. Anyway, back to .22. They just seem pretty well balanced compared to other the other calibers I shoot. Largest I have is .30. Im also a fan of heavy .177s but .22s just seem to be my go to most of the time.
 
For me, I intend to get into .22 cal soon. Like another poster said, I started with .177 and stuck with it because of higher velocities and ammo compatibility with my other airguns. There was also this thought that .22 was so much more expensive than .177 to buy, which I recently found is not the case. They are roughly the same price, and anything less than a buck difference per 500 isn't something to care about.

With that in mind, I want to get .22 for something different, and maybe pest control. Never even considered the bonus that they would easier to handle and load.
 
I shoot .177, .22 & .25.

.25 hits hard out of my Hatsan break barrel, makes big holes in paper. Not affected by wind. Easy for my big sausage fingers to load. Not readily available locally but not expensive to shoot good quality pellets if you shop around. Takes some serious energy to get it moving, the Hatsan takes quite a bit of effort to cock. Not something I’d be shooting every day.

.22 is a good compromise, big enough to hunt, wide pellet selection. Wide gun selection. 


.177 is pretty universal, cheap to shoot, the widest selection of guns including smooth bore revolvers that shoot BBs. A good long distance shooter out of pumpers and break barrels. And there’s some nice inexpensive .177 air guns

Personally, I’m a believer in multiple calibers for multiple uses. You can’t argue that a 1/2” wrench is best. It’s only best for certain uses, that’s why wrenches come in sets. If you have more than one airgun, having both .177 and .22 makes sense. 

If you stick with .22 only, that’s going to restrict your options for pellet pistols.

 
I'll +2 to the above. I havent owned any other caliber besides .22 I think in about 2 years in my PCPs. Used them from 12fpe to 45fpe. Just love them. Lots of good choices and cheaper than .25 or .30. I think a higher power .177 would be fun but not 100% sure I want to go there. Now I do have a HW30S in .177 that I wouldn't change that caliber.