All Good Things was a great double episode, but we all knew it wasn't the finale and didn't really feel like one.
To be fair, they -knew- they'd have movies coming up. So they just ended on an epic episode rather than a conclusion. Which they accomplished well regardless of what you think about the TNG movies. None of the other episodes have this excuse. Might be an interesting poll if you replaced TUC with Turnabout Intruder.