I'll be the lone wolf here and suggest you watch it all. Don't cherry pick episodes, at least not with this series, as others have said it's a highly serialized show and you will be lost. For my money, the first half of season 3 where all the "heroes" are being rounded up was the best outside of season 1.
^That was the second half of Season 3. FWIW, if the OP's intent was to watch approximately 44 episodes, watching that many straight through would get him halfway through Season 3.
Damn that was a good time back then. "Save the cheerleader, save the world" was such a cool and mysterious tagline and the episode "Company Man" has got to be one of the best character twist episodes i ever saw. Shame it crashed and burned so hard after the first season.
It's a choir. Just watch the first season. It's not worth your time watching the rest, unless you like watching great shows go bad.
I enjoyed seasons three and four as well as the first one, but the second was messed up partially by the strike and even more by a bad storyline IMO. But I thought the premise of ordinary people with extraordinary abilities trying to live normal lives, wasn't dispensed with at all.
Yeah, watch the first season in its entirety. Seasons 2-3 just get more progressively painful. I didn't watch S4.
I think it's a watchable show for the most part throughout, but it's just not a very good show and not anywhere near the quality of the first season. For what it's worth, I thought the final season was the series in a microcosm. It started off decently strong before going completely off the rails. My view on watching only the first season is more a statement that it's better to just watch the first and stop than it is to watch only parts of the first.
Watch Season One, the first episode of Season Two, the final episode of Season Three and then Season Four. You can skip the rest.
2-4 isn't unwatchable as much as a disappontment compared to 1. (And season 1's finally, to me, was really disappointing...more so than several episodes of 2-4) Seasons 2-4 had some good ideas, but not reaching season 1 heights. Some of the ideas i liked -- the "old" gang of Heroes and they're plans vs. the next generation The season 3 stuff with Sylar (was it 2) seemed kinda goofy. Season 4 (like season 4 of Andromeda & Earth Final Conflict) was getting back to what we liked. Robert Knepper did a great job of building a manipulative villain...it felt like his motivations/skills disappeared in the last 1/3 of the season or so . if remember right, Sylar teaming up with Peter was interesting jack cole of course does great as HRG, transforming him into a conflicted hero definitely the last episode should be "essential", and absolutely the last 5 minutes, as the series wraps up like it began (like Lost's last 5 minutes).
As everyone else has said, the show is highly serialized. You just can't skip episodes if you want any hope of the show making sense. Season 1 is the best.