What's the sweetest boat you've ever sailed on?
By that I mean, a boat that is well balanced, can be easily trimmed to hold a course on her own, without an autopilot or a hand on the rudder. A boat that doesn't pound in sloppy seas. A boat that sets her shoulder in a blow, and then politely holds it.
A boat that is simply sweet, well-mannered, a pleasure to sail on. As opposed to some that have a very narrow notch where they are well-trimmed, or need constant tending on the helm (like a J/24).
I'd have to say the most well-mannered one I've sailed on yet has been the Islander28, which even Bob Perry said was a wonderful surprise in terms of how mannerly it was. (And the basis for a number of his later and larger designs, for that reason.) It may be relatively heavy, and the builders did tamper with the design (changing the keel-stepped mast to a kludged deck-stepped one with an offset support), but it balances quite easily and then continues to sail itself, with no one on the helm. Something I haven't seen done on any number of boats from any number of makers, both larger and smaller.
So what boat has particularly impressed you? Not for being fast, not for being any one thing, but for being so well-mannered that it puts others to shame, and shows how boat design really is an arcane art.