1986 28.5
I've owned a 1986 28.5 deep keel version (5'-2" draft) since new, and feel it out performs many boats a couple feet larger. The shoal draft 28.5 and 28 are likely similar with slightly less pointing ability than the deep keeled 28.5.
Interiors would be about the same.
The 28 has a taller mast and fractional rig (maybe easier to handle short handed), while the 28.5 is a mast head rig and can be fitted with larger head sails for much better light air performance.
Obviously, they have the same Yanmar diesels. Unless you are interested in racing a deep keeled 28.5, I'd go with the boat in the best condition with the most added equipment. Check out
www.huntertwentyeightfive.com.