For factory ammo, you definitely want to try the hornady v-maxes. Don't rule out the 50-grainers tho, try. Winchester super-x seemed to s**k, velocity varied so much it ran a line up and down the target (3.85" @ 100 yds) perfectly lined up tho. Winchester ballistic silvertips seem ok, and federal is usually fine, HSM from cabela's might really be something you want to try tho.
All of my factory load expirience comes from the .222 rem, 30-06, 308, 220 swift, and someone elses 22-250 (savage sporterweight don't kno what twist).
It all comes down to what YOUR gun likes, so don't be surprised if it shoots great with what someone else says is crappy. I would recommend Hornady first, then if you are able, try the 22-250 cartridges from Hunting shack manufacturers.