Meh, I liked all 11 films. I judge them on an individual basis. Having said that, I prefer the first 6 because they were special. They brought back characters from a show and existed primarily because fans really wanted to see them. Each movie was a) an event and b) thought to be the last adventure. Because each one was thought to be the end (except TVH), there could be character development because there was no future continuity to consider.
When TUC was done, the publicized assumption was that "TOS films will end and when TNG finishes up, they'll slide into movies." No fan demand, no begging, letters, or anything. Just make movies 6 months after the 7 year old series finally petered out. Plus, nobody was saying "this movie is the last one." They were planning on making them over and over, so a certain status quo had to be maintained Also, finally, as it was said on this thread: there's was no "need" for them.
But, again, I like them all.
I think you nailed my own thoughts beautifully. I liked them all, too, but those first six were indeed quite special. They were a critical part of my childhood. The original cast films came out of a very strong desire from fans to see those characters return. The TNG seemed to be largely an act of what Paramount probably perceived to be just common sense, the next logical step in that particular franchise. Doesn't mean they weren't good. They were just built differently, and for different reasons.