I'm not crazy about DS9's finale. There were a lot of problems with it (some good things, too), but I think the main issue was that the writers were too concerned with wrapping up the plot(s) and not focused enough on the story. Sisko at the beginning is charged with getting Bajor into the Federation and being there for his son. So in the last episode he seemingly voluntarily leaves Starfleet, Bajor, and his son to live with the Prophets. And poor Jake, abandoned by his father...it just didn't seem right.
AGT, on the other hand, had a pretty thin plot, but did a great job of thematically wrapping up the TNG story.
As far as overall quality, I'd put TNG, DS9, and VOY all on the same level, each excelling in some areas, with ENT slightly behind them.