Personally, mine is joint first between Sandshrew (the cutest), Espurr (most relatable), and Gastrodon.
After those, in no particular order, I like Turtwig (best starter, fight me), the Roggenrola line (little rock guys), the Litwick line (candles and lamps with nefarious intentions), and Metagross (cool robot thing).
hard to pick just one. Flareon just barely eekes it out to the top but it has the unfair advantage of being my first starter, from Gale of Darkness on GCN. my fantasy team would be
Flareon
Swampert
Decidyueye
Gallade
Drampa or Altaria
Alolan Dugtrio or Clodesire