They're neck and neck. Insurrection has a dumber script, but Nemesis makes sad. Insurrection would be instantly better if the B'aku weren't pacifists. Watching the middle-aged cast defend a bunch of settlers that have no will to defend themselves fills me with disgust. The S'ona should take the planet since they're the ones with the will to fight for it.
I'm guessing you didn't like that Data died for literally no reason at the end of Nemesis in what is retroactively now the *second* worst ripoff of Wrath of Kahn. (Thanks again ST:ITD) And fair enough, nobody did. But the premise of Nemesis was at least decent. It *could* have been a better movie if it had been handled better. And several of us have all now given our opinions about how Nemesis could have been better.
The premise of Insurrection (and I know you know this, but I'm recapping it for effect) was that a bunch of asshole hippie aliens living on a planet with unexplained magical healing properties that basically rendered them immortal (and to be clear, the planet was not originally theirs, they're fucking squatters) decided to utterly shun technology, to the point where they would not even allow their own people who liked technology a little bit more...
i.e. the Son'a, Let alone Federation... to even use the healing properties that the *entire planet* they're squatting on had. They weren't even taking up much of the planet. Hell, there were literally only about 600 Ba'ku- All living in one tiny village on the magic planet.
Remember, this movie took place in the middle of the Dominion War, which wasn't necessarily going particularly well for the Federation at the time.
And then the entire Enterprise crew all unilaterally decide to declare treason against the Federation to help these fucking assholes, just because one of them gave Picard a boner. This is presented as a good thing for some reason... Even though the Ba'ku are *literally* the bad guys here if you're looking at the conflict objectively. I guess they aren't as ugly as the Son'a though, so the Enterprise crew are totally justified.
It also makes no fucking sense that the weak-ass pacifist Ba'ku were able to force the Son'a to leave the planet, when they're literally the same species, except for the facts that the Son'a aren't pacifists and don't shun technology. If anything, the Ba'ku should have been the ones forced off of the planet.
And I'll say it again, they literally could have both shared the fucking planet. The Federation could have even shared it with both of them, to heal anybody hurt in the Dominion War.