I've built 5 10/22's and have a bunch pending completion now. I've tried a few bbls and prefer the Whistle Pig ones. For the money and if you're not thinking serious competition, Green Mt is good, very good, for the money.
Now, that all said...if you're to get into this 10/22 kick, go to www.Rimfirecentral.com Search, read, search, read, etc... It's ALL been asked there.
I'd also suggest thinking about what you want out of your completed 10/22. Looks, performance, both? Is it for general plinking, informal target use or competitive use? After you decide, decide what you are willing/able to spend on it. Don't build thinking resale, it's not there on these to amny ppl's surprise and disgust. When you've gotten result and cost decided on, start looking. You'll be tempted and that can easily lead to spending more and in the end running out of $ or spending way more than planned for. Could be good, could be bad. You can easily spend more on a single part (bbl, trigger, stock) than you originally paid for the gun.
most impt...have fun!