We have a character that we don't know nothing about, internally, other the fact that he's mom is human, his dad is Vulcan and he some some underlying issues that show a a potential, major, problem with his biracial identity.
Then we fast-forward ten years into the future and we have a character who's pretty much dead set on ignoring his humanity, going forth with his Vulcan heritage by purging emotion, and spends an entire movie realizing his place in the world.
Then, once Spock finally has himself figured out, he dies.
Well, that just sucks. It's like reformatting a computer now and that's what happens in III. We now have a reformatted computer; his characteristics, personality, everything is now gone. And now we have someone who now has to not only find himself but where he lies in the lives of others. Then, after ten years, Spock finally comes into himself again. Not only that, he is comfortable with himself. Something that he never was before.
You can't really, or I personally can't, decided if Spock-post TWOK is better than the Spock Pre-TWOK because the series of movies, excluding V because that was just a Kirk-circlejerk of shit, is a journey through Spock's development. Spock in the 60s show is pretty damn flat but his character is molded and evolved through the movies, through his rebirth.
So yeah, I like Spock before his death and after his death.