Disclaimer: this is in no way a comprehensive view of the entire year of TV. This is only the stuff I care enough about to lay stylus to screen for.
Some of what I used to watch has given way to stuff I am more interested in. Some things I used to be really excited about took weird turns, like Grimm...not sure if that one will be redeemed. So here we go.
Castle: after a shaky~ish start with a missing Castle drama, the show got back to its roots, and the season finale was a thing of pure beauty. It was such a good, fulfilling piece, that if Castle weren't already slated to return, it could serve as a more than adequate series finale.
The Mysteries of Laura: I picked this one up on curiosity, and stuck. The finale opened up several new questions, but they were all ones I still want answers to. That being the case, it's still fresh and interesting, the characters still people I care to know more about. The little cliffhanger with Jake's evident memory loss will be interesting to see play out.
Arrow: season 3 ended with Oliver hanging up his hood... forever??? And going off to live happily ever after with Felicity. This after he destroyed Ras Al Ghul, and saved Starling city. This could be an acceptable series finale, with the hero satisfied his work is done and leaving his legacy behind. It's that "Dark Knight Rises" wrapup. I'm truth, the show has a long way to go to get from the hood, to the arrow, to the green arrow. And I am not sure how they are gonna get there, but I'm looking forward to seeing the next step.
Agents of S.H.I.E.L.D. : we are left with Hydra initially dehydrated, then rehydrated by Grant Ward; The Inhumans defeated for now. Skye revealed as Daisy Johnson, AKA Quake, and about to get her own team of enhanced agents. And Simmons, on the verge of finally having that first date with Fitz that we have wanted since 5 minutes into season1...getting sucked up into the new macguffin. All that and Coulson down a hand.
Brooklyn 99: Captain Holt relegated to PR, and Jake and Amy kiss... and who is the new captain?
Once Upon a Time: and the new villain is... Emma Swan!
Supernatural: not the strongest season closer, but standard for the show. Renew the Winchesters bond, and introduce the big bad for next season.
The Flash: I had high hopes for this show, and for 23 episodes, it DID NOT DISAPPOINT. For all the grim and purposeful darkness of Arrow, the Flash started on a note of heroic idealism, and held that note without getting corny, or self conscious. In the season finale, we have kind of an unnecessarily dire cliffhanger, with Barry racing into a world devouring vortex. Is he fast enough to stop it? If not, it will be a really short season 2.
Forever: I liked it, thought they left it on a good note, but I guess I wanted a little more before we closed the book on Henry, Abe, Jo, and Lucas. I'm sad it cancelled.