I’m never sure worst is that easy because so many of them are so bad. Best is Wrath of Kahn that’s a gimme, but TMP, The Whales, Kirk finds God, Cracking Borg Makeup, and Nemesis are all serious contenders for worst.
Of course then there’s the challenging second half of the question: Defend Nemesis as the BEST Trek. That’s where you really get to watch someone’s wheels turn and learn how they think.
I dint like rath of kahn so much in that it reminded me of a TV episode, not a big screen movie
First Contact I like a lot, and the new ones with the young Kirk and Spock were great!
The first MOVIE star trek still is great to watch.
I guess that is my criteria- would I watch it again (and again) I must have watched First Contact the most of all about a dozen times at least