I love Lost in Space. Truly. But I’m convinced The Anti-Matter Man is so well regarded only because the 6 or so episodes before it were so dire.
Try watching it after the first few episodes of the first season. Everything’s so over the top. Guy Williams shouted every line even before his evil double arrived... The robot moaning about how ugly he is...
Oy. Shave 10 minutes of BS from this one and it’s really solid. For Lost In Space...
It's actually a fun show. In ways, season 3 has aged the best as I keep returning to it the most on the blu-ray set. Season 1 is robust but dated at times. Season 2 just tries to copy and paste the formula of "Batman" without a clue and fumbles at almost every turn. The one inside the robot is kinda fun, as well as the one with the tiny robots taking over (even if budget meant they all look like the Earth creation B-9, oddly... ) It's easy to see why Jonathan Harris switched gears to make Smith more a bumbler than a truly nasty villain - which probably aggravated some fans at the time...
"Anti_Matter Man" was a high point but they missed out on some opportunities to make it even better. No evil Will... And good grief, no heroic Smith to complement "our" Smith! And definitely listen to the cast commentary on the blu-ray, it never got stale...

But, yeah, what's up with B-9 whining about his go-go appearance where he wouldn't be out of place in a white room with black curtains?
"Visit to a Hostile Planet" was a little campy and OTT but still highly enjoyable and in some scenes very well handled. I'd put that on top of "Anti-Matter" solely because it did more with its potential...
"Time Merchant" - for LiS - is also remarkably good, if not dated.
The one where Smith and Don end up being prisoners together was rather good...
The one with the hippies (one where hippies rule the planet because they can't grow old and apparently need to drain children's blood to find a cure for non-aging) is as warped as it is frightening. It just could have been told a ton better, Smith's wig was stupid, and for seeing go-go guys in the background with the pool table-turned-operating-table (!!) how come Penny was subjected to go-go girls? (This was the 1960s, everything was heteronormative without a second thought, and season 3 was cutting budget corners all over the place - even for Irwin Allen's standards so they weren't trying to hint at anything, not for a young kid's show made over five decades ago.)
The other hippie/beatnik one where they're rebels was irritating as heck yet
fun for some bizarre reason that I cannot explain. Wasn't that the one with Lyle Waggoner (best known for Wonder Woman, among other things?) playing a robot?
Heck, even season 3's opener - logic gaffes aside and a few exist, unless the episode was heavyhandedly saying how such a reform system would not work to the point they all get to keep their weapons at time of incarceration (as well as typical 1960s anti-computer sentiments generously on display...), also had some solid moments in amongst a hit-or-miss bag...