Welcome!
My understanding is that DPMS was "the best kept little secret" of AR-15 "clones" untill very recently, when their high quality and reasonable price range became relatively widely known.
A new-comer with a very promising profile is S&W's M&P 15 series, probably comparable to the Bushmaster line.
Colt, of course, is a superb product although, I suspect, we wind up paying more simply for the brand name; this is not to detract from the fact that it is probably near the "top of the heap"!
A lesser known (and relatively less expensive), but outstanding weapon line is from Stag Arms who, incidentally, put out the S&W rifles.
Building your own is an excellent alternative if you have the inclination, capability, tools and above all, some experience, in order to remain safe. Of the companies mentioned above, Stag Arms has an excellent parts line, but there are many others!
Educate yourself on legal matters if building your own (e. g .in many locations even owning disassembled, separately stored full-auto selective fire AR-15/M-16 conversion parts without special permits is considered a crime!). From the reports I heard, the "authrities" tend to be fairly unsympathetic and inflexible in these situations.
Good luck, be safe, and welcome to the addiction! Now, you are living the dream!
Victor.