I voted for Saga Of A Star World Parts 1-3 and brought us into a two way tie for the lead with The Living Legend.
Saga is so epic, and just a little bit into you are starting to care about the characters - very well done.
SOASW is my all-time favorite as well. No episode since has ever felt so BIG. Saw it in theaters several times (as well as on TV) and IMO, it played VERY well on the big screen.

My close runner-ups would be "Living Legend" and "War of the Gods", but the pilot was so rich and epic in scope. I'll never forget the viper launches in glorious "sensurround" sound (essentially a subwoofer that would kick in during in the loud moments; causing the floor to rumble). Even as a solo film (and not a series' pilot) it worked
beautifully.