To give you a recommendation, need a bit more information. What is your intended use for the rifle? carry rifle? longrange prone gun? something in between that can do both?
Here are some generalities though....
Barrel: from my experience, most of the popular custom barrel makers are producing great barrels. Krieger, Hart, Bartlein, Brux, etc. You don't go wrong with any of them.
Twist: definitely 1:9. This will allow you to shoot everything up to 180grain bullets. My 280 is odd because it only likes the light bullets (140grains) and heavy (168). It does not like anything in middle (150, 162)
280AI vs. 280Rem - I lean more towards the 280Rem because you don't have to do any fireforming (which eats away at barrel life)
If you want to build a longrange capable carry-rifle, here's mine:
My 280 - Updated!