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
Always been an Arbok fan. Sure, Gen 1 he dies to Psychic really easy, but especially as we get into Gen 3/4 and you get stuff like Fire/Ice/Thunder Fang TMs as well as decent Dark moves to teach it, it becomes a nasty piece of work with some support. Plus, it gets Intimidate and I love Intimidate as an ability.
Gen 1, everything dies to Psychic.
Not Dragonite, but dragon type was even more broken than Psychic
Until you meet Lorelei.