From a historic top team standpoint, they are pretty much on par with the SEC or BIG and have pretty much won as many NCs as either conference. In the BCS era they made it to 7 NC games - would have been 11 if not for best team losing in conference championship game - second only to the SEC. Other than FSU the ACC is less than good. Really from top to bottom the Big 12 has as good or better teams than any other conference. Last year Baylor and TCU were as good as anybody, OK State and OK were almost there too, and K-State was really good. If they could get it together they could have a really strong conference.
However, these are the same teams that presided over the breakup of one of the oldest and most storied conferences in college football - The SWC.