Tough call between Insurrection and Nemesis. I picked Insurrection because it just was plain boring, and this scene ruins the rest of the movie for me. I don't think I need to say anything else about Insurrection....
This doesn't mean Nemesis was any better. In fact, it was a poor way to end TNG, and the TNG\DS9\VOY era on film. The very idea of Shinzon was insulting to me. An insane, dying clone of Picard usurping the entire Romulan Empire? Really? Then he wants to destroy Earth for no reason? Lame. They could have had pretty much had the same movie, but substituted Shinzon for Sela, and it would have been 10 times better. OK, Sela isn't my favorite Romulan, but at least it would have made more sense to have Sela as the villain. After Q, and with the Duras sisters dead, Sela is the closest thing Picard had to a "nemesis" in TNG. And with it being the last TNG film, would have been a re-union of sorts to have Denise Crosby.
Also, the idea of having B-4, without a single reference to Lore, was stupid.
You know what? Change my vote to Nemesis, Please!