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).
Kyogre is the best legendary in my opinion
Piplup for its cuteness. I also like its evolutions.
I also really love Bulbasaur and its evolution line. That was my starter back on Blue on the Gameboy. Venusaur with Leech Seed then whipped everything into submission pretty much. Tanked like a mofo!