Voyager
As much as I enjoyed Voyager, I think it broke the system so they can't go forward unless they go on the reboot timeline. Voyager came back after 7 years in the Delta with so much new tech. Quantum slipstream which will let them get anywhere really, new shields which even the Borg had trouble with, not including the fact they instigated a Borg civil war followed by killing the queen and trashing stuff. Also Warp 10.
Where can ST go from there? They can now explore vast areas of space, okay, more vast, they have new tech which probably made Voyager the most powerful ship in Starfleet when it got back (and therefore the most powerful ship in the Alpha quadrant).
A followup I'd like to see is the Federation going back to the Delta quadrant and fixing the issues that the Caretaker (and then the Federation and other Alphas) caused, sort of a "Janeway caused this, we have to fix it" sort of thing, maybe with the children of the original Voyager with Wildman as Captain and the Borg boy as Commander, Torres being engineer.
Biting the hand that feeds IT
