I chose Squirtle for several reasons:
A. My friends were starting with the other two
B. I like Raikou better then Suicune, or Entei
C. Squirtle is good against Brock
D. Also good against almost all the gym leaders
E . Squirtle is by far the best for the Pokemon League
F. I usualy start with Charmander, so I wanted a change
G. Learns bite, wich is kind of helpfull