I left Wow after 5 years, and i'm really enjoying the difference with STO. I remember during the early days of Wrath, myconversations with my friends were generally about how i was beginning to dislike the direction of Wow. That it wasn't about my character any more and simply about my gear. There was no distinguishing players bar just a different chest/shoulder piece etc, that my journey from vanilla to TBC to Wrath just became a 5/6 day raiding grind to be replaced 3 months later with the same over again.
I love the unique characters we have in STO. How i can walk around ESD and see so many races, even Na'vi and Darth Maul (i forgot who you were but you looked great ), bio's that really give character weight and belonging. If people are that creative in character designs, imagine what Foundry will bring us later. I'm not a Trekie yet but i'm starting to understand what its like being one. JJ's film really brought me into this world and DS9 is what i'm watching now, though Voyager is still my favourite so far. I love the Intrepid and i finally have one in game now I have so much to see but i'm greatly enjoying everything so far.
You can bash WoW all you want, but I think Cataclysm was a tremendous step in the right direction for WoW. The new quests (in new zones as well as revamped old world zones) are more story-oriented, and give you the feeling that you're actually affecting the world. And story is usually what attracts me to an MMO. (That, and the ability to play a short race.)
I'm not going to stand here and say that WoW is better or that STO sucks, though. They're different games. Both of them do things correctly, and both of them do things incorrectly.