Marc Daniels and Joseph Pevney both directed 14 episodes, making them the most prolific of TOS directors. Are there any other directors you liked, based on their episodes? One of my favorites is Joseph Sargent (The Corbomite Maneuver), who later went on to direct the original version of The Taking of Pelham 1-2-3.
Senensky, by miles and miles, followed by Daniels and I guess Pevney. Senensky is the only guy who for me has all winners, plus they are mostly memorable winners. Even THOLIAN, where he only did half the show before getting fired, is pretty darn good.
When it comes to television I tend to pay more attention to who wrote the script than who directed but looking at my favorite episodes I will have to go with Joseph Pevney: He directed two of the best episodes that take place "somewhere else" in this case depression era US in City on the Edge of Forever & Vulcan in Amok Time. I actually felt I was being transported somewhere else from the usual in these episodes. He directed the best comedy episode in Trouble with Tribbles I also really love Immunity Syndrome and Journey to Babel
Joseph Pevney. Just too many good episodes. Devil, City, Archons, Arena, Fridays, Journey. But John Meredyth Lucas only directed 3, but they were 3 great jobs. The Ultimate Computer Elaan of Troyius The Enterprise Indecent