With the movies I've always enjoyed Generations
(and the Shatner books that were spun-off from it), along with First Contact
As for the two part episodes, Birthright
, even as a kid I preferred the Data storyline/DS9 crossover, while Worf's storyline was rather tedious and boring; the producers had a good thing going in Part 1, but then they really dropped the ball in Part 2 with just making it a Worf story and no follow-up to Data's story in Part 1. I remember watching Part 1 on tape the morning after CHRO had aired it (I remember that I was really, really sick that weekend so I had gone to bed before the episode aired), and the following weekend I tuned in, all excited too see what would happen to Data, but instead we got the stupid Worf storyline.