Truth to tell...after finally being able to see TOS...I LOVED IT...it is down and out the BEST of ALL the Star Treks!
TNG is a very very close second...but they just didn't have the dynamic between characters that could compare to that between Spock, Kirk, and McCoy...and they certainly didn't have any Scotty.
Now I was bored with DS9's first few seasons...though I think those seasons overall were more true to Gene's outlook on Trek...
I did like the last few seasons of DS9...and thought it kept up with the characterizations and the Science Fiction questioning of what made a person, or individual, and what our moralities were.
I actually loved Voyager more than DS9...probably because overall it kept with the Rodenberry premise of episodic series. However, I hated the Kazon, and thought that they overused the Borg. I too thougt that the repeated use of a single species, or keeping an ongoing storyline actually decreased how good the show was.
Now that they've taken it to the extreme, in Enterprise, I think it's absurd. Not only do they throw out all continuity, but they also don't really have the writing effectiveness of the DS9 staff to actually do it. I've tried watching and finally, after analyzing it all, figured, the writing is just plain bad. It isn't just continuity errors, it isn't just that they have an ongoing storyline and forgot about episodic writing in Rodenberry style...but the writing itself is rather bland, and not all that interesting.
Heck, I even liked Nemesis (I thought it was actually one of the better trek movies...despite what a lot of people think), but Enterprise is too linear, to predictable, and too badly written for my taste.