You won't go wrong with any Air Arms spring powered rifle. If you can't afford one then you'll have to get a German Weihrauch but it won't shoot as nice out of the box.
Muzzle energy being equal there's nothing to chose between .177 and .22. No difference in wind drift. The .177 will shoot flatter. Zero at 30yrds and you'll be more or less point blank from 15 to 35yrds and with anything over 10.5ftlbs at the muzzle you'll be fine taking brain shot rabbits out to 40yrds.
.22 will of course hit harder and give the impression of a cleaner kill but you'll have to make sure you learn that loopy trajectory. I've got a few (8!) air rifles... including two Weihrauch, a Diana and three Air Arms. I only hunt with the Air Arms these days. .22 tx200hc with a M8 6x42 Leupold (reparrallaxed to 30yrds) on top and a .177 ProSport with a Vortex 2-7x32 rimfire scope. Both brilliant combos. ProSport was dear but boy what a rifle! Picked the TX up 2nd hand for £200. Proper yeomans tool. I'll have both of them forever.