Howdy! For this premier post I am going to rank and briefly criticize each Star Trek series.
4. Voyager: By sci fi Tv standards Voyager is not a horrible tv series. It is not a particularly great one either. This show did have a good premise and a promising cast of characters, but it largely failed to live up to its potential. All too often this series felt like a weaker rehash of TNG which is unfortunate, because It could been a much more memorable series if it moved away from the TNG type storytelling (not to mention Q and the Borg!).
3. Enterprise: Its somewhat challenging to judge this series because it changed radically three times during its four season run. Therefore I'll breakdown this show into three distinct sections:
Seasons 1-2: ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ.....Despite the change of setting to the 22nd century these two seasons for the most part felt like rehashes of previous Berman Trek Series. The show was also handy caped by a fairly boring cast of the characters, the ill conceived temporal cold war arc, and a lack of truly great episodes and a surplus of episodes that were either just god awful or boring.
Season 3: I am not a huge fan of the Xindi war as I think Deep Space Nine's Klingon and Dominion War story lines were much better war arcs. That said, this season was a definite improvement over what came before.
Season 4: This is for me where Enterprise gets really good. The fan service could be a little much at times, but in general the various mini arcs from this season were good entertainment and it was great to see the show finally living up to its premise of a being a prequel. If the rest of Enterprise was this good than the show would be up higher on this list.
2.(Tie) The Original Series: Here it is, the one that started it all and boy is it a good show! It certainly looks good when paired with other old space operas like Lost in Space or the original Battlestar Galactica and a lot of these episodes really do stand the test of time. There is also a lot of crap that is only watchable for camp value.
2.(Tie) The Next Generation: If your from my generation than the Next Generation was Star Trek. It was an enormous success and for good or ill, it set the template that all subsequent series were to follow. Was the show any good? Yes, after a couple of shaky seasons it became a pretty good scifi series. The main problems with this show is that it has a pretty boring cast of characters (With the exceptions of Picard, Worf, and Data) and it could be pretty formulaic sometimes. Because the characters themselves were boring the show usually needed anomalies or aliens of the week to generate most of the drama or tension. This worked for a while due to some good writing, but the continuation of this storytelling into later series proved pretty deadly. I also must say that the Trek universe of TNG seems kinda bland compared to the more colorful universe of TOS. It is also TNG that started the horrible sonic wallpaper soundtracks that would infest every following Trek series(Rick Berman must have hated Star Wars simply for the wonderful music!).
1. Deep Space Nine: This series will never be as well known as TNG, which is a bit of shame as it was a much more entertaining show. After a couple of akward seasons where it was it finding its legs, this show developed into the best Trek of all time. It had great characters and utilized them far better than any other modern trek. It also had mostly good storytelling, relying more on its characters and continuing plot lines rather than random alien/anomaly of the weeks to drive the series. It also has Captain Sisco, which is probably the closest we will ever get to having Samuel L. Jackson pilot a Federation Star ship ;).