I don't have any best show ever really.
I like most of them.
Babylon 5 was okay to watch, the various Star Trek series, that's pretty much all I've really seen much of now that I think about it.
Seen alittle StarGate, seems like an okay show too, but seen way too few to make a good judgement on that.
Problem is, I eventually get bored of watching them, especially if they go once a week, which often is the case.
Star Trek: Enterprise is the only series I've seen all episodes of, and that's largely due to having all episodes available to me to watch whenever I want. The past 2 weeks I've almost been sitting glued to the screen every available hour(s) I didn't work, plowing thru it.
Was done with all episode the previous weekend.