Choosing the perfect starter is one of the toughest decisions in the entire game. So which one is the better one? Well, there IS no better one over the other. So what does it go by? It goes by your preference, game experience and which game you own.
Let's face it, would you want your starter to be a dull Grass type? Or how about an awesome fire-breathing Pokémon!? ...Yeah, I thought so. One of the most exciting and most popular starter types is, you guessed it, Fire. With high Special Attack stats, a Fire type can dominate the battle field easily. But that's overall. How about we take a look at the first few Gym battles with this starter?
For example: In Generation I, one of the first hazards to travel through is the Bug infested Viridian Forest, an easy battle for the Fire starter. However, the first Gym Leader is the Rock type. As any trainer should know, Fire is weak against Rock, so the Fire type isn't looking too good right now. Even after that, there is still the cave with many Rock and Ground types to deal with and no Grass or Water types to catch until way later. Even taking a look at the Generation II games, the first Gym Leader has a Pidgey and Pidgeotto with the Ground move Mud-Slap. After that, the rest of the game is a breeze.
With the Grass and Water type Pokémon in more abundance and Fire types more rare, wouldn't you want to start off with the one type that is the most difficult to find?
Often, the sprites of the starter Pokémon play a role in our judgement. Some people prefer cute, strong or just a good looking sprite. Doing research on the game sprites of the starter options available to you could help you choose which starter you want to use.
A Rod, let alone an Old Rod, is not obtained at the start of the game. Even catching a Magikarp would not be that useful: you still have to train it to level 20 to teach it Surf or any Water type move! And we all know how annoying Splash and Tackle can be for awhile...
It goes without saying that choosing either Fire or Water could be the smartest strategy to adopt in any Pokémon game. Ultimately, it is up to the individual trainer to choose their starter that they will work best with.