I'm thinking of going stainless.  Which is the better choice for a Bushy, a new Krieger barrel or a complete upper from say...DPMS.  

That is a pretty apples to oranges comparison. Kreiger barrels are cut rifled, hand lapped, cryo treated, basically about top of the line. DPMS barrels are mass produced button rifled. This is NOT to say that DPMS barrels suck, but with the Kreiger you are paying top dollar for an excellent barrel and with the DPMS you are getting a mass produced barrel. A lot depends on what you plan on doing with the rifle. If competition shooting, the Kreiger is your better option (among others as well). If just casual plinking, informal target shooting, the DPMS will serve your purposes just fine. There are also other very good stainless options other than the Kreiger or the DPMS.