Season 1 👍
Season 2 👍👍👍
Season 3 👍
Season 4 🤢🤮
Season 5 🤨🙄🤢
Season 6 👌 so far
I highly suggest watching seasons 1-3. They are funny, yet very serious at the same time as well they have great character development and great action scenes. They show great teamwork and use of powers showing what they are actually capable of.
Seasons 4 and 5, on the other hand, are absolutely the worst seasons in all the Arrowverse. They try to be funny but aren't. If you find most of the humor to be funny you are an immature little child. The plots are stupid and go way off track. The characters are terribly developed. Sara is a terrible leader. The team doesn't work together as a whole any more. They rarely use their powers and there are no great fighting scenes any more. It is child's play now and the show is god awful. The show is an absolute embarrassment, now.
Season 6 was actually much better than seasons 4 and 5. Bishop, the villain, is by far the third best big bad of the series. I still didn't care for the concept but it was executed reasonably well. Much of the SJW went away, they started working as a team again, Nate got his brains back, the humor (or lack of) wasn't nearly as forced and Avalance wasn't forced. There were some annoying political snaps, but they weren't big enough to ruin the season. Still be nice if they stayed away from politics unless historically accurate like they once did.
Season 6 was still not near season 1-3 quality, but if season 7 quality is as big of a jump from 6 as 6 was from 5, it will be close back to season 1 and 3 quality. It still needs more suiting up and action, as well as less politics. I don't regret watching season 6 like I do season 4 and 5.