I voted Pascal, but Phineas is second place. He's a mysterious man.
I think you meant to put Dr. Shrunk instead of Frillard, although Frillard would also be a fitting name for him. Frillard was in CF only (and implied to have died according to some fans. I think he's just retired).
While I am always happy to see Phineas because he brings badges, I think personality-wise my favorite is actually Nat. I love his sophisticated, British-sounding dialog. He's also so cute and unique, being one of very few reptiles in the game.
Phineas and Pascal. I don't see Phineas often anymore because I have most of my badges but it always put me in a good mood, I would like to be able to hug him, he looks like some mascot. Pascal always have some funny and philosophical quotes, he's cool, floating in the ocean.
I love them all but either Phineas or Pete - Phineas is adorable and I love the excitement of getting a new badge, and Pete is such a classic AC character to me that seeing him always makes me feel really happy and nostalgic <3 it?s also nice that we can only catch him at certain times of day, and his dialogue is always fun!
I've gotta say Saharah! I enjoy getting exclusive items from her and her dialog is funny. Stumbling across her running through town is always a good day.