On Youtube Nutnfancy does a great review of the 15-22. His favorite model is the MOE. He talks about the MOE having a match grade barrel and the earlier 15-22's having lighter or tapered barrels.

So what's the deal on 15-22 barrels? The 15-22 is going to be my next weapons purchase and I'm kind of leaning toward the MOE version because of bang for the buck. Time I upgrade a standard threaded barrel model it would cost as much or more than the MOE. That is unless I find a lightly used threaded barrel model on the cheap. Then I would do the sight, stock and swivel upgrades.