I recently did a big Trek rewatch/first watch, stating with TNG. I’ve seen all of this multiple times. Then DS9. I moved countries during its run and missed entire swathes of episodes, much more than I realised, so it was great to complete that. Voyager I fucked off after a few seasons originally, but watched them all on this rewatch, and was pleasantly surprised, although the very end is weirdly underwhelming. I’d say just for the sake of Lower decks if nothing else, find a guide to beat and/or essentially episodes and have them watch those. You’re probably looking at 7-10 eps per season.
I also caught up on Discovery, Picard (I’d binned it after season one, but watched two when three was about to come out) and SNW.
I didn’t bother with Enterprise at all as I don’t remember liking anything about it. I tried getting through the TOS, but couldn’t, even though I had enjoyed all of those as a kid.