Hi Rodney,
I use the Contax 210 lens, and in my opinion it is a winner. The lens excels at close range, such as tight portrait shots, so not to be compared with something optimized for landscape distance. It has the closest focusing distance of any other medium format lens of this focal length. The 210 has beautiful color rendition and smooth tonal transitions. Autofocus is slow but accurate on the Contax 645.
I have seen a few posts indicating less than expected performance for the 210 lens. It could be a poor sample, or a loose mount, or an uncalibrated flange distance, or even improper technique. My copy appears sharp from corner to corner, and I could not be more happy with it. The only "flaw" about this lens could be the lack of a tripod collar, but that is not a deal breaker.
David