Seriously.... bullseye competition with my target .22 auto, it's Eley Match Ammo. Target shooting with my bull-barrel .22 rifle, it's CCI mini-mag or CCI Blazers. They each provide the best groups in their respective guns.
Plinking or casual target shooting, it's the Federal bulk-pack stuff from Wal-Mart. 550 rounds for 9 bucks. The accuracy is more than adequate, and it's as cheap as you'll find it. It's what I feed the 10/22, the Single Six, and the Standard Auto.
It isn't important if I like the ammo, but it is important if your gun likes the ammo.
The "best" .22 ammo for your new gun is the ammo that the gun shoots the best. Some are great with the cheap stuff, some aren't. Buy several brands and types and let the gun tell you what it likes.
I have three .22's, two revolvers and one semi. None of them like the same ammo. I'm trying to find a middle ground ammo that is cheap and shoots well in all three. May take a while, but the testing will be fun.
I've found that my Mark III 22/45 likes Winchester .22LR much better than the Remington .22LR I've shot thru it. The Single Six will shoot anything I put in it. I think once I run thru all of the Remington, I'll buy up more Winchster ammo to use in both guns.
I like the federal bulk 36gr Hp and winchester Xpert HP
My S&W 22A shoots the federal stuff into tiny groups and my savage MKII shoots the xpert stuff into 1/4" groups at 50 yds.
My 10/22 only likes cci mini mags so it doesn't get shot as much as the other 2.
If you got the convertible model, then you just have to try some 22WMR's - any brand (I use CCI). They are expensive (by comparison) so I don't shoot them that often, but sometimes you just want a little extra kick!
For my 10/22, the cheap stuff. Accuracy isn't a big concern when a 50 round banana is attached. If the target needs extra punishment, Remington Yellow Jackets or CCI Stingers make nice holes. For my 77/22 and MKII pistol, Winchester seems to give me the most consistent grouping without breaking the bank.