1. TUC
2. TWOK
3. TSFS
TSFS has a number of plot issues that didn't need to be, but there's so much more in its favor that it's hard to dislike. Saavik's quick to damn David about protomatter is all for nought considering Genesis was tested using lifeless planetoids and not a teeny tiny starship loaded with energy-producing dilithium, antimatter, and other goodies that would NEVER have been taken into account.
TWOK is indeed excellent, especially for its time. It too has plot issues, some more easily addressed than others. But a movie that has such an awesome villain, well-played by Ricardo Montalban no less, and the story has the guts to never put them in a room face-to-face and yet the tension remains so palpable...
TUC - Maybe I saw it in a way others hadn't at the time. I dunno. As far as swansongs go, this one is strong - even though they forgot that Excelsior had the equipment to detect gaseous anomalies. (Never mind the bizarre tailpipe reference, unless she was so enamored while wandering around 20trh century Earth before finding Chekov's
noocooluhr wessols that she'd utter such an arcane term and hoping everyone else would. Granted, it's the same movie that makes her the butt of a joke because she's the linguist who can't get Klingon right, har har, but I digress
.) Add in General Chang, ably played by Christopher Plummer (who embraced the role and created dialogue for Chang as well), and not since Khan has there been such an impressive and compelling enemy. That's a HUGE feat, especially since Trek - to this day - still hasn't created a villain that comes close to either Chang or Khan (TWOK). Best dogfight in the franchise as well in a scene to be savored. Over and over and over again.

Seriously - all that tailpipe stuff just wooshes over at warp speed, given how tight the battle scene is. Ditto for the TNG Engineering set being used in place of the TMP original. And the soundtrack was magnificent. The original release disappointed me because it was incomplete, but the re-release a couple decades later with all the tracks more than made up for it.