Ahhh, the ACTUAL worst episodes of Star Trek. Although I still don't think Spock's Brain deserves to be in such disreputable company. I'd even put it over something like Wink of an Eye.
Replace "The Alternative Factor" with "Turnabout Intruder" and that's pretty close. Never cared for Lights of Zetar and found it a bit odd. But, I enjoy "The Alternative Factor" as a bit of a crazy adventure.
To be clear, I'm not claiming that "Spock's Brain" is among the five or even six worst TOS episodes. At least, I'm not claiming it right now. When I was much, much younger, for a period, I thought it was the worst, is what I'm saying. Now, I've "matured," by which I mean that I see things from a certain other point of view, and I've reevaluated it several times. It's at times fun and also funny, which places it light years ahead of certain episodes that are neither. That list is just those of that at one time or other I've called the worst, not what I think are the five (or six) worst.
Regarding "Wink of an Eye," several years ago, I reevaluated it also, when I found myself actually enjoying it. I'd picked it for rewatch, to see the TOS-R changes, and because I didn't often watch it, because I'd ranked it as so awful. But the way Deela interacts with Kirk is actually quite sizzling and fun to watch. Forget logic (logic is a little tweeting bird, chirping in a meadow), the scene on the bridge when Kirk accelerated, with the Dutch angles, the ambient hissing sound, when Deela zaps Kirk's phaser off into
hammerspace after side-stepping its beam, that scene is actually loads of fun. When Kirk and Spock meet after Spock accelerated, they exchange looks and it's as if they held a whole conversation in a second without saying a word. The triangle between Rael, Deela, and Kirk is on a level of character interaction rarely attempted in the series. I could go on, but these elements and others mitigate what is one of the lesser episodes. So, I've since reappraised it, and it's risen some in my (theoretical) list of rankings. Oh, and it has the scene with Kirk putting on his boots. Yeah.
As far as "The Alternative Factor," there are some good ideas, that maybe, possibly could have been made into a good episode. I love the UFO in the other universe. The end is very mythological with the Lazaruses at each others' throats.
