>>28441347Well, when it comes to starter Pokemon specifically, to begin with I already have a bias when it comes to typing: I want a Pokemon that is reliable in that it should probably be able to take even a big hit; meaning most Fire-types are out by default, since their stat spreads tend to be more on the sweeper side. (God fucking dammit I could complain all day about how weak and useless Chimchar is when used ingame instead of in competitive with minmaxed stats+LifeOrb.) Also Fire is a specialty type that a balanced team will almost never need for coverage. So we're left with Water and Grass type starters, out of which I tend to find Grass far more interesting; Water tends to fall into a rather plain role of balkin' hits and hitting back with Water/coverage moves. A lot of the time Grass provides alternatives like status moves or curiosities like Leech Seed. So on the gameplay side I prefer to pick Grass.
The other side is simply whether I find the starter's design cool, which is why I might occasionally choose other starters like Cyndaquil in gen 2 (since both it and Chiko are really adorable).
That's just how I pick starters; other favourites are either just designs I really enjoy or buddies I've found by playing the games and using a wide variety of monsters. Like, how can you say no to a giant deadly butterfly?