I enjoyed ST: The Next Generation very much (and the other spinoff series were ok), but for my money the original Star Trek was the best. Yes, the special effects were primitive by STNG standards, but I think a lot of the original series' plots played so very well to the overacting of Shatner and how he interacted with the rest of the cast. Ultimately, all the Star Trek series are good, although I will say I found it hard to connect with Enterprise, the one with Scott Bacula.