Gen 1 felt... meh to me. Movie aside. The overused repaints really annoyed me. Beast Wars did a far better job with characterization, used very very few repaints(Cheetor and Tigartron were it?), had tons of really cool moments, excellent and consistent animation, and actually made things like death and life feel extremely meaningful.
The one thing I'll give Gen 1 is "The Touch"'s usage, but that's it. The Headmasters stuff was cool, and I won't lie that it deserves credit for a lot of stuff. The introduction of the Predacons, for instance. Or the combiners.