Next Generation is definitely my favorite, and still fighting with Game of Thrones for my favorite TV series of all time. I greatly enjoyed Deep Space Nine and Voyager as well. I even thought Enterprise was pretty good, although it's hard these days to get into The Original Series with how dated it is (and, contrary to popular belief, about half of TOS isn't even that great, I think).
The games have been incredibly mediocre though. But if you're a big fan of all five series and you love the lore of the prime universe, STO is a great game to play. It has throwbacks, references, and even quite a few actors reprising their roles as their characters (Leonard Nimoy, Michael Dorn, Jeri Ryan, and Aron Eisenberg come back as Spock, Worf, Seven of Nine, and Nog for example). It's also great that its story is a true post-Nemesis continuation, unlike the new series of movies.
Nice. I've been to a convention once in Chicago, was really awesome. TNG>Voyager>ToS=DS9>Enterprise for me.