Deep Space Nine for me.
Voyager at a close second; the other three a distant third.
only thing NG was missing was 7 of 9. other than that the sheer power of Picard and Data carries it. could it have done without the obnoxious little brat? sure. could Troi have been hotter? sure. did everybody hate the doctor and silly-beard Riker? of course. weird props on LaForge and Whorf? hell yes. but Picard going home and breaking down after having been a Borg cancels all of that out.
oh, and Q. he was NG. damn stealz0rz...