Next Generation and the like was just crazy in that every dang away mission planet just so happened to have a gas mix of 70% N, 21% O2 and the rest CO2 and inert gases at like exctly 1atm (or at least a mixture within those norms)

That was just what TOS, TAS, the movies etc did - mostly for production cost reasons. It's also why there were transporters, though I personally really like the idea and it's not a Star Trek specific thing.

I don't think Enterprise was more realistic per se, just set in a much lower tech level much closer to current day. Some parts of Sci Fi aren't "realistic" in the way if you showed a 2023 cop show to someone from 1800, they'd say it was a bunch of flights of fancy in tech (modern cars, planes, smartphones, zoom meetings etc would probably seem as realistic to them as starships do to us).

Honestly, rankings have to be almost completely subjective at a certain point. IDK if you listen to any of the Star Trek review podcasts, but there's always tension around how to rank a show. Do you try and be "objective" and take your personal enjoyment out of it as much as possible, and instead rank on production success (did the final show do what they were trying to do?), cultural impact?, Iconic level of an episode?, Number of Iconic episodes or well produced episodes or the average quality over a season or show?

Like, there are episodes that are a LOT of fun, say "Trials and Tribulations" from DS9, but it didn't really have a strong unique plot or sci fi conceit or have anything to "say" in morals. It was Iconic solely to big existing fans, and the awesomeness of the production was entirely around the technical achievement of filming in the 90s using 60s techniques and near perfectly splicing together with existing footage. It's one of the ?2? DS9 episodes I'm at all interested in re-watching frequently, and it's really really fun for me as a huge Star Trek nerd. But is it a "great episode"?

Compare to "In the Pale Moon Light" or "Measure of a Man", or "City on the Edge of Forever". Those are Iconic for a reason, and most of them work pretty stand alone. They're arguably "better" in context, but they have pretty good production - it seems to achieve what they set out to do, they have a message, they have a moral idea they're playing with, and they throw in some Sci Fi too.

Then there's the same thing but over an entire show. I think TOS and TNG and DS9 had very high highs, but also some pretty low lows throughout the run. "The Alternative Factor" or "Code of Honor" don't exactly stand up as "better" than Picard. By Voyager, I think they still had a bunch of 3/10s but mostly avoided 1/10s, and honestly Enterprise seemed to hit that middle 4-6/10 range very consistently. I haven't "done the math" but I'd be willing to believe if you averaged ratings of every episode, Enterprise might well rate higher on that average than TNG. It's just that if you're selective you can watch probably 30 episodes of TNG that are 8-10/10 and there might be 2 in Enterprise.

I will say - if you like reading, and you like SNW a lot - I'd suggest trying the novelizations of TOS and TAS by James Blish. They fix all the production limitations of 60s tech and budgets, but keep the good stories and characterizations. It's actually how I got into TOS originally, back before streaming or releases of the show on DVD. I think in many ways I wouldn't love TOS as much as I do if my main exposure was actually the episodes. Balance of Terror as a case in point basically bored me to death in the middle where for the 52 minute runtime they just linger in a countdown set of scenes for way to long. Similar for The Trouble with Tribbles - the reason they could slice it up for the DS9 inserts is there was like 8 minutes of a bar fight you can mostly cut and lose NOTHING. For on screen - the TOS Movies really cemented them IMHO.