I think it's really interesting how the different seasons each have their own character.
The first one shows us how the whole crew / ship relationship comes together in the so-called "Cluster". Each of the main characters is introduced, and the setting of the Lexx Universe is established.
Season two, where they basically bumble around the "light side" of the Universe, features very nice, mostly self-contained stories in each episode.
Outstanding (in the sense of "sticking out") in this Season: Brigadoom. A lot of fascinating ideas, like the whole setting of the planet Potatohole. They could have come up with a different red thread to hold it all together than Mantrid, i didn't like that too much.
Then season three, with the fascinating sets on Fire and Water. I especially love the scenes they filmed in the old cement factory near Berlin and the Tunnels in the 19th century fort. (Episodes K-Town and Tunnels). The overall story has an interesting philosophical twist, too.
And then the fourth season, with the mocking of the political situation on earth. Very different, but i liked it. There are some outstanding episodes, too, like the Midsummer's Nightmare. Fortunately they kept a possibility for a return of the show. Would be great if we get to see more Lexx in the future.