I loved Babylon 5 until the Vorgon solution. I sat there for 10 minutes with an empty feeling in my stomach. I could never sit through another episode. I spent years watching the series, getting pulled in deeper and deeper then....... I was so disappointed.
SG1
Farscape.
Star trek TOS.
In that order IMO. Firefly would be on that list if they had more episodes.
SG1:Ark of Truth is pretty good, albeit fast-moving. Should be out next month on DVD.