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
Kalos
Floette is a favourite while Florges is placed much lower as I think that going from Flabebe (little fairy thing in a flower) to Floette (fairy thing is big and holding the flower now) is much better than the final evolution to Florges, oh no Floette is now the flower. In my eyes, the final evolution should have been either Floette now holding a much larger flower due to increased power or simply ending at Floette, giving a two-stage evolution line (possible with stat buffs to Floette).
There’s a reason why there’s Mega Floette and no Mega Florges, Floette’s design is much more iconic.