>>27239794This.
Fire is rare, while water is common. Further, many fire types have major flaws (Numel and Slugma spring instantly to mind), while the starter has a certain guarantee of quality. Even if you find a fire type, there is no guarantee it will be good.
Water does have the benefit of not needing to look for a Surfer later, but that is about it. The single biggest argument against most water starters is Gyarados. Gyarados is almost always available, and available early, and is fucking awesome. Oshawott was the only starter to not have this disadvantage, and sure enough, Oshawot is considered the least of three evils.
Grass tends to be between the two, but Grass Type starters are awful for playthroughs, mostly because of Grass Type Movepool Syndrome. The Grass starters tend to be on the better end of the spectrum of Grass types, but they are still pretty bad. If there is any of the three starter types you can ignore in-game, it's most certainly Grass.
