(Sub-Hot Take: Curtis was the better Saavik)
To me, this is a tough call: Curtis definitely looked more Vulcan/Romulan, and played a far better Vulcan. Kirstie Alley just didn't look Vulcanoid to me, though she definitely played the disposition of someone who was a Romulan/Vulcan hybrid A LOT better, IMO. But then, as far as I know, her Romulan heritage isn't canon, so, some points get awarded back to Curtis. Long term, Alley has too much baggage. But then, for my family, so does Curtis, because of a very awkward masturbation story she told at a convention we went to where she was a featured guest. LOL.
I think I'd have liked it better if the protege in Star Trek VI had been Saavik, yes, and then also if Saavik had been played by Kim Cattrall or maybe someone else entirely the whole time.
Unpopular opinion: "The Wrath of Khan" is plagued with errors and really silly plot points that haven't stood up well over time, and were honestly pretty noticeable when the film came out, and we've all excused it because it was awesome to see Star Trek with action on the big screen, and there were enough positives to balance the problems out.