Oh, this is going to be a long list. So let me just order yours on the ones I watch as well, sorted by how much I like it.
FireFly
LOST
24
Dollhouse
Warehouse 13
The only one from the above that's still running and hasn't ended or cancelled, it Warehouse 13.
Though, I am exhausted by 24, glad it's over.
Dollhouse should have had another season.
Warehouse 13 should have been cancelled earlier.
LOST had a great run. Some seasons of it were really properly fucking cool.
FireFly. That's worth a whole separate forum.
What I recently started watching is Hell on Wheels, Luck, and about 500 more shows.