Dervish Dancer Bard
Dervish was one of my most played classes in 3.5 and the Bard archetype had the most flavor while adding the utility of the Bard spell list. Also, the fact that nothing really forces it into a Dex build allows for some fun concepts like a Hammer Dervish.
Raven Master Ranger
The Falconer archetype was underwhelming, but this gave a lot of bird based flavor. Useful, flavorful options that replace a lot of the Ranger class features I never really cared about.
Knife Master Rogue
Knives are awesome for flavor, but mechanically super underwhelming for a combat Rogue. This made them a viable option, and turned the Rogue into the best option outside of fighter for their iconic weapon style.
Titan Mauler Barbarian/Titan Fighter Fighter
These could probably benefit from the more generalized archetypes, giving martials access to oversized weaponry. Big weapons are cool.
Thunderstriker Fighter
This archetype always appealed to me, the image of mixing a heavy blade with a small shield and shifting focus as needed is amazing. Loved the idea of running it with a Bastard Sword for increased adaptability.