I agree that "The City on the Edge of Forever" is overrated, but I still think it's a good episode. As far as TOS, it's hard to say what is overrated and underrated. I haven't been on this board very long, but I haven't seen too much discussion over the episode "Devil in the Dark". That is probably my favorite TOS episode and I couldn't even begin to tell you why. If this is actually fairly enjoyed then please correct my perception.
I do think "City..." is one of the top TOS eps, but I wouldn't say I like it any
more than my other top TOS eps, which include "Devil in the Dark", so I agree with you there.
I really think that "The Best of Both Worlds" two-part episode in TNG is a little overrated. I do find myself skipping these when watching this series. I do watch it on occasion, but it's never been one of my favorites. I really enjoy the episode "Schisms". I think it's kind of an ode to current speculation over alien abduction theories. It's also just an interesting sci-fi story. Like I stated earlier, I'm really unaware if "Schisms" is well liked.
I can't speak for anyone else, but I think "Schisms" is fantastic. I don't think it's generally considered one of the "classics" of TNG with BoBW or "The Inner Light", etc., but I can't recall seeing very many people say it was subpar, either.
I don't think there are any bad DS9 episodes. They're all great.
Have to disagree with you here... DS9 is my favorite series, but "The Storyteller", "Let He Who Is Without Sin," and "Profit and Lace" are all terrible.
TOS: Overrated: "Space Seed". It seems to be hailed as one of TOS' classics, generally, but I found it to be mediocre-to-bad.
Underrated: I don't spend much time in the TOS forum, so I may simply be re-stating what is already a popular opinion, but I've always thought "Balance of Terror" was one of the greats.
TNG: Overrated: I
like "The Inner Light." I think it's a good ep. I don't think it's this series-defining masterpiece that I have very often seen it categorized as, and it wouldn't make my personal top 10.
Underrated: I think "Conundrum" is superb, and definitely underrated. It probably WOULD make my personal top 10 for TNG.
DS9: Overrated: "The Visitor" - as with "The Inner Light", I certainly think this is a good ep, but that's
all it is to me. It's not a benchmark/watershed/what have you, and again, wouldn't make my top 10 DS9.
Underrated: I've always really liked "Body Parts." It presents interesting character developments for Quark, while at the same time being a really fun ep with a lot of really hilarious moments (Quark and Garak in the holosuite come to mind).
VOY: This is tougher, in a way; I'm not sure there is as much "consensus" on what the good and bad VOY eps really are, apart from a few standouts. So, I'll take a stab, but I may be way off here...
Overrated: "Maneuvers". I've seen this mentioned often as one of Kenneth Biller's better eps; personally, I think it's a subpar ep that demonstrates why I don't think much of Biller as a writer.
Underrated: "Vis a Vis." I don't see this ep being discussed much at
all (positively or negatively), and I like it for some reason. It's not AMAZING, but I think it's fun with an interesting premise.
Don't know or care enough about Enterprise to include it.