Whatever shoots accurately in the gun I'm using. Then I file the noses flat with a Hanned SBG tool. You can't get that tool anymore, but you can get the Paco ATS tool or Accurizer tool that will flatten or hollow point .22 bullets here:
http://www.pacotools.com/I'm sold on using the flat nose .22 ammo on squirrels. They don't crawl away to die in the nest or on a tree limb like with some .22 hollow points.
If you're hunting with a .22 revolver, pick your .22 ammo based on bullet diameter. There is a lot of varience here and revolver throats can be on the large side. Most of your bulk .22 ammo is small to work in semi-autos without jamming. I like CCI Blaser in my Single Six Bisley. Some old Eley High Velocity stuff I have shoots really well and packs some serious punch, but I can't find it around here anymore and it's expensive now.
My Ruger MKII shoots about anything very well, so I usually just use Remington Golden Bullets that have been flattened.
Be careful if you use standard velocity or subsonic ammo in a handgun with a short barrel. Some struggles to break 700fps from my 5.5" MKII. Hardly a good choice for killing stuff. When the barrel reaches 15" or so, things change and the ammo will kill just fine trucking along at around 1000fps with a flat nose.