TOS is too haphazard, and rather rubbish for the most part.
TNG is too happy happy america, as it were.
DS9 is too derivative.
Voy is too, well, rubbish.
Ditto, Enterprise.
X-Files started well, then collapsed.
Never watched E:FC
Ditto Farscape
Lexx could and should have been much better; they never really got over the gimmickery.
Firefly never had a chance to get going.
So we're left with B5.
Which, excluding Crusade and the first 1/2 of S5, was great.