If you had asked me this last year I would have said Gate, no doubt. SGA was showing its last season and the prospect of a new Stargate series was on the horizon. Then Stargate Universe started and turned out to suck hard, not only that all prospect of any new Stargate movies based on SG1 and SGA died.
Trek on the other hand, each and every series from TOS right through to Enterprise have all been either good or at least watchable were as Universe is totally unwatchable and frankly an insult to those that stuck with SG1 and SGA for 15 series.
So I have to go with Trek simply because it hasn;t produced a version that has been unwatchable and as a die hard Gate fan, until Universe started, you don't know how hard it is to say that.