Nothing wrong with the .25 caliber - if that's what you have in the safe and have a good stock of ammo for it the just keep on smiling!
The .22 is my caliber of choice. For the energy I need and range I do my shooting it's more than adequate.
I did buy one .25 caliber airgun - an FX Royale 500 - for larger raccoon and porcupine sized pests but don't shoot it that much. It's a beautiful airgun and very accurate but my Impact easily matches it for power.
Guess that ammunition is the main consideration. I've been shooting .22 forever, it's readily available, there's a huge selection and most importantly, it's a lot less expensive than the .25.
I'm just getting into bench shooting and went for a .22/700 Panthera. I know that a larger caliber would have an advantage but I'm shooting for entertainment and happy to accept the handicap. My backyard range is only 128 yards anyway.
Think the .25 is a great caliber. For me, it's more than I need.
Just my perspective.
Cheers!