I'm not a big kit person anymore, but I do enjoy the occasional Accurail kit. Detail is decent and paint pretty sharp for the price. Wheelsets and couplers are plastic, however, so I do replace those. It's not as high quality as a Genesis or P2K, but they're a great and easy kit to work on the coffee table while watching TV in the evening. The silver SP "Overnights" boxcars and the EL and IC boxcars in this picture are Accurail (sorry I don't have any close-up images handy):
Are Proto 2000 kits (gray box) out of production? One of the hobby stores near me still has quite a number of those in stock. Very good detail, but in my experience, they require patience. Some years ago I bought a set of 8 or 10 hopper kits with NAHX markings. I only built about half, stopping due to my frustration; no matter how careful or how sharp a knife I used, I couldn't avoid breaking several grab irons or rigging lines on each one trying to get them off the sprue. But they're great kits if you have patience.