Well I may be biased since I own a 1986 30U.
I got interested in looking at a Nonsuch when I wanted to step up from my Bristol 24. I had a good discussion with the Captain of the boat we had chartered on for a winter vacation back in the early 1990's. He had delivered a number of Nonsuches for a dealer and was schooled as a marine architect. He liked them for their simplicity of design, no stays to worry about and all lines come back to the cockpit including reefing lines.. Not a lot can go wrong with them. No mucking about on the foredeck until it's time to pick the mooring or anchor. He also said they were very well built. As others have said lot's of room below and good headroom (I'm 6'2). Lived aboard mine while working in New York City for about five years from April to December and loved it. Tough little boats. A book called WITHOUT RIVAL chronicles a Nonsuch 30 that was abandoned on the return leg of a Trans Atlantic crossing near the Azores and drifted over to Central America. Owner retreved it and is still sailing today.I finally bought mine in 1995 and have not felt the need to look at another boat since then. Love it even more now that I have converted it to electric propulsion. Would never think of selling it until I can no longer sail it.