Re: O'Day DS or Flying Scot?
We went from our first boat, a Sunfish, to the Day Sailer II, and would highly recommend it to you.
The DSII has a self-bailer (only works whilst the boat is underway), whereas the original DS had no bailer.
Ours also had the optional mast tabernacle, which made trailering and set-up much easier. In fact, easily done singlehanded.