Shows that deserved a second series

Forever

Firefly!

EDIT! Woops- maybe I should have fully read your response LOL.

I added a 2nd so.

Journeyman - I felt that the show's mythology was just beginning to break into really interesting territory.

Wolf Lake - I don't think the network quite knew what to do with it, but I found it quite charming.

The Lone Gunman - I was so happy for such unconventional protagonists to take the stage on their own show, which I felt they'd really earned.

Kolchak: The Night Stalker - Darren McGavin is delightful and the show was creepy and fun.

Chasing Shadows - I was drawn to it because of the "Who" actors involved and wound up really enjoying it.

Dracula with Jonathan Rhys Meyers.

Boomtown. Takes the standard cop show and uses the narrative technique of Rashomon where we see the same events from the POVs of different characters to only gradually learn what has happened.

Freaks And Geeks

My So Called Life

The Good Guys

Almost Human

Terriers

Luck

Vinyl

Studio 60 On The Sunset Strip

Skin

Rubicon

The Fades

Jonathan Strange & Mr Norrell

The Adventures of Brisco County Junior

Now and Again

Babylon Project: Crusade

Uh, no.  Crusade was messed up by network mucking in its first series.   I'd rather have a proper FIRST season, before I'd ask for a 2nd.

"Who do you serve? And who do you trust?"

Absolutely, a remounted first season and then a second series to follow that, at least. It never even really had the chance to get a decent opening, I thought at the time that this would've made a pretty good substitute. Blake's 7 mixed with Yamato and The X-Files (or Han Solo as captain of the Enterprise) sounded amazing, I wish we could've gotten five years of quality like "The Path of Sorrows". There are so many unanswered questions regarding the Box, the Earthforce conspiracy, the technomages' connection to the Shadows, etc.

"Is this the end or the beginning? Where does the universe end? Where does it begin?"

UFO is another. Gaudiness aside, it probably had one of the most complex depictions of a First Contact War on television at the time where no one might be on the right side. It might've been cool to see it revived in the actual 1980s and deal with problems from that era alongside UFOs. I can remember a really nice bit of fanfiction that had Straker team up with a Russian Spetsnaz team to retrieve a downed ship in Afghanistan and another one that had him come up against alien conspiracy debunkers. There was so much to play with in that universe, particularly regarding SHADO's international efforts to maintain their shadow war and the aliens' attempts to expose them.

I forgot about Space: Above and Beyond. But Harsh Realm should have had a complete first season lol