Cyndaquil is the easiest starter to beat the game with, as it learns good attacks early and it's effective against several of the game's Gyms, but late-game, it's rather weak. As Typhlosion, it has pretty good stats, but a shallow movepool. They are much better Fire-types, such as Growlithe, which are available early on.
Totodile is a great choice. It's not as powerful as Cyndaquil early-game, but by the time it's Feraligatr, it has access to a huge movepool, and its stats are great too. There are a lot of other great Water-types out there, though--there aren't quite as much Fire-types and Grass-types available.
Chikorita is very, very week throughout the entirety of the game, being weak against the majority of the game's Gym Leaders and Elite Four members. As a Meganium, it's a defensive Pokemon with a rather good movepool (Outrage, Earthquake), but it's still weak to a lot of types. If you want a challenge, go with Chikorita.