Insurrection. My explanation? IT CAN'T BE SAVED.
If fan-editor Anti-Matter has shown us anything, it's that there's hope for Generations, and hope for Nemesis. But Insurrection's flaws run SO DEEP that there's no hope for it. Just the very conception of its premise, the implications of the morale etc.
The other two have good premises, but bad execution, which can be corrected by a good fan-editor. And if you need any more reason, watch Linkara's review.
yes, I think you've hit on the key. It's the only one that really would require going back to the drawing board and doing a major re-write to fix.