Both of these are dated designs. Of the two I suspect that the 38 would be a better sailing boat. I really think that there are better sources for designs than Roberts, but some of this reflects my own tastes and prejudices.
To answer your question fairly I need to explain my own tastes and preferences. These are my opinions on subjects that frankly do not have one universal always-right answer. To begin with, I am fan of truly traditional boats and also, although seemingly contradictory, fast lightweight modern boats. By traditional boats I mean boats that authentically draw off of the principles of actual historic craft with a high degree of integrity. I do not like quasi- traditional boats that wear their sense of tradition like tail fins on a 58 Caddy. I also like fast/ modern designs that have their own sense of integrity. I find both types of boats fun to sail but for very different reasons. I have owned both types. For my current life style I cannot imagine owning a traditional boat again but I truly do love them.
As to other designers of home build plans that I like, I think that Van de Stadt from Holland does a nice job. Some of their designs seem to be IOR based, and as such, do not appeal to me as much as Van de Stadt''s more straightforward cruising designs. Van de Stadt has a very strong reputation for quality engineering and has designed some very fast boats in their day. I think they offer some of their designs on disk so that they can be computer cut saving a lot of time and perhaps money. From what I gather they are a class act.
Yves Tanton in Newport Rhode Island does some very nice work. I think he is a very creative designer with a very nice eye for visual proportions.
Dudley Dix from South Africa is a very interesting designer to me. I have never seen any of his boats in real life (that I know of) but he is terribly creative and seems to understand what it takes to design a nice performing boat that is also a comfortable cruiser. I like his Black Cat 38, which is a wooden boat.
One of my favorite designers of traditional Boats is Antonio Dias. I have sailed his boats and they are really nice designs. I doubt he has a stock plan that is in the size range that you are considering though.
How could I forget Charlie Wittholz? I actually worked for Charlie Wittholz in the early 1980''s. Charlie did some very nice, very interesting traditional designs in steel. Charlie was a neat guy. He actually worked for Alden and Rhodes before opening his own shop. I liked his work. His boats had a certain simplicity that was very elegant. He had a nice eye for proportion and a sweet
line. Hard chine boats are actually very hard to design so that they look right. The chine forms a strong accent
line that has to work with the desired hull shape, the physical properties of the plating and the other visual
lines of the boat. Charlie was able to keep these sometimes-contradictory
lines under control to produce attractive traditional craft. While I liked most of Charlie''s work, one of my least favorite boats of his was a bilge keel cruising boat. (I drew many of the drawings for her) This was a purpose built boat for the European canals and as such was a good boat for its purpose but was not my kind of boat. Charlie and I would have lively lunch time discussions on our divergent points of view on modern lightweight boats. We both loved wood as a building material. I loved his stories of Alden and Rhodes. Rhodes was very much a patrician gentleman but Alden was a very colorful character.
Charlie made the final passage to Fiddler''s Green a few years back. His family still sells his designs by mail order. I don''t know if they have study plans but he used to have simple list of designs that listed the basics of each design. I believe that their phone number is 301 593 7711. Also WoodenBoat still markets some of his designs.
Bruce Roberts is popular but I am not a fan of his work. It is not so much that I do not like his work per se. I think that for the most part Roberts designs conservative simple boats, but to me they are dated. His Spray series have less than no appeal to me. Having read about the original Spray and the sailing ability of some of the so- called copies of her, I have come to believe that Josh Slocum made it around the world despite the short comings of Spray rather than because of her sterling virtues. Josh Slocum was the consummate seaman. Spray was a coastal oyster boat. Why anyone in this day and age would want to use her as a model for a whole
line of boats is completely beyond me. But I emphasize this is only my opinion and Roberts has sold a bunch of these things so my opinion is not shared by everyone on this.
Roberts more modern designs were probably good designs in the 1970''s but a lot has happened since then. To me his design ideas have not advanced as well. That said, Roberts has a boat he calls a 434 that someone built as a long range single-hander that looks like a nice boat but slightly dated to my eye. Still in all these are very heavy boats and I strongly believe that weight, in and of itself, has no inherent virtue and is a very serious liability.
At the risk of sounding like a broken record, much of the questions in sailing have no one right answer. That does not keep people like me from having strong preferences and opinions. My opinion suits me, and the way that I choose to sail, very well. It may not suit you at all. It is easy for someone to refute my opinion on some other criteria than my own. As I have said before on this BB, ultimately that debate can have no more substance than a trying to prove that Vanilla ice cream is inherently superior tasting than strawberry ice cream, (which is why these are called ''opinions'').
Good luck Jeff