Is it worth going Scimitar on a dex build still? Are the Scimitars "better" than the kukris or rapiers? I know the magic Estocs are few and far between.

magus scimitars are rather common. I do prefer longswords myself, but that's with a lot of metagame. For the 1st play-through scimitar is totally the weapon of choice. Rapiers are ok, but there are no really incredible ones. Estocs are better come endgame, but suffer from availability. Kukris are abundant from nok-nok quests, but are rather underwhelming when it comes to enchants.

TL;DR. Scimitars for the 1st play-through are the best choice.