well im trying Pokémon FR/LG on a ROM I Found and it runs great my choice right now is to pick which one to start with Either Charmander, Squirtal, or Bulbasaur.
You should use Bulbasaur, it will work great on the first two gyms especially giving you a quick start, and I always considered it kind of overlooked as a starter with everyone going for Squitle or Charmander instead. Well, that's how I remember it anyway.
I've chosen bulbasaur as the starter before, only problem I had was the elite four and had to try training a dragonite to get through. I've also learned that each of the starters is like a difficulty level, as charmander is the hard level as it struggles a lot through the gyms, squirtle is the medium and bulbasaur is the easy level since it has little difficulty getting through the gyms. In my opinion, I'd choose Squirtle, as it can deal through a lot during the gyms and E4.
Try not to get Charmander everyone gets charmander its not even that great squirtle is agood choice and bulba is a good choice but neither are very good agaisnt the E4