Although I think the Andorians and the Gorn are cool, I excluded them because we didn't really find anything else about them in TOS besides humanoid warrior aliens with antennae and hostile anthropomorphic lizard aliens, respectively. The first really interesting Andorian in all of Star Trek
, and we find out very little about him indeed. (That said, Nalder was great in the minor role of Shras.) We have to go all the way to Shran to get a real live-action Andorian character. The Gorn captain speaks, and it's interesting as far as it goes, but in my opinion he didn't constitute a dynamic character, and rather he served only as an exposition delivery device.
The TOS aliens I focused on were, in my opinion, much more interesting than just their superficial traits, and we actually find out something about the characters of their respective species. The only exception was the Tholians, whom we really learned nothing about, but their coolness factor (via the visual effect and Babcock's multi-track voice performance) was so great
that I couldn't help myself.
Furthermore, with a single exception, I discarded the humanoid aliens as patently uninteresting.
To recollect (having gotten straight which forum/thread this is; in my defense, I posted in another thread around the same time about aliens in general), so far I've nominated:
the cosmic cloud from "One of Our Planets Is Missing"
Vulcans would have been excluded for being pointy-eared humanoids, except that their culture was so very interesting and Spock is my favorite character in all of Star Trek.
I'm not saying that people are wrong to find humanoid aliens interesting; I'm just explaining my thought process.