AckImp

This comes up regularly. Very few off the shelf semi-auto .22LR rifles exist that will compete with a good bolt action. However, look a bit further than club experts and plinkers, and you'll see an awful lot of medals won with semi-autos, in comps that are equally well suited to a single shot or manual repeater. A good quality barrel, matched with good quality ammo, on a 10/22 will shoot amazingly well. It all depends what discipline you intend to shoot. If it's just for plinking, a good semi-auto's more fun, and will shoot almost as well as a dedicated target rifle that might not be any use for any other disciplines you end up wanting to try.

.22-250

As others have said, SK stuff is really good. I've used 10s of 1000s of Standard Plus and it's always been good. Recently I've tried some SK Rifle Match and it seems to be slightly better and only marginally more expensive.