For me, it would be insurrection.
I just found it to be incredibly boring, I think most people will pick Nemesis but I found that to be at least mildly entertaining at times.
The only forgivable thing about Insurrection is the hot Trill who gives Riker the eyes.
Same here. Insurrection is easily the worst of the four. And for me, the only "forgivable" thing about that movie is Jerry Goldsmith's excellent score. I'm still waiting for the extended CD to come out.
I don't understand all the hate Nemesis gets either. It washed away the bad, bad, taste that Insurrection left in my mouth, so in that regard, it was a success. The only real bad thing about that film was Data's stupid, pointless death that did nothing to advance the plot in any way. But otherwise, it was fine.
Plus, it ALSO had an excellent Jerry Goldsmith score, for which I am also waiting for the extended CD.