Oh, I really only ever liked/used the Nelson-class scout, Larson-class destroyer, Anton-class cruiser, and Loknar-class frigate when it came to their “original series” designs for Star Fleet.
They all seemed to me to fit the aesthetic of the TV show. Almost all the others looked hideous and/or ridiculous to me. Plus I never thought there needed to be so many different classes of starship–but I always ran a “small UFP” Star Trek based on what we saw on the series where it (to me) never seemed like the UFP had hundreds of starships gallivanting around the galaxy as was depicted in later media.
But I was referring mainly to their adventure modules and sourcebooks being more interesting and imaginative to me than the various series and movies we got post-The Undiscovered Country.