How can someone even think of abandoning their starter.
I stick with my starter always, like if it was my own Pikachu.
Besides, it's my only Pokémon who always get a nickname, I hate giving nicks.
These have been my starters each generation:
1st Gen: Squirtle
2nd Gen: Totodile
3rd Gen: Torchic
4th Gen: Piplup
5th Gen: Snivy.
And in the future 6th Gen I've already chosen Froakie.