Ericson, Tartan, Morgan
I've had a T-37 for eleven years, love the boat. Ironically, I looked seriously at all three that you mentioned and chose the Tartan. The Sparkman/Stevens design has beautiful lines and sails great. One thing you need to look at for cruising is tankage. The Tartan has 50 gallons of fuel, 90 gallons of water plus an additional twelve in the hot water heater. I think the Morgans was respectible, but I don't remember the Ericsons. The other important issue is stability and the ratios.