Well, I love many starters, and Hoenn was my first, so you'd kinda expect me to swing towards them,however...
*image removed*
(Kanye voice)"Yo, starters, I'm really happy for you and I'mma let you finish, but Charizard is the best starter of all time. The best starter of all time!"(/Kanye voice)
I mean, he was practically the strongest pokémon in the anime, unless you think Harrison's Blaziken was better as it defeated Charizard. In the manga, Charizard is a beast, and Green's Charizard rarely loses - it only really properly lost once, to Red.
He's also the only flying-type starter, has two good attacking stats and good speed, a brilliant movepool, and looks the coolest out of all Gen I starters, closely followed by Blastoise, then leaving Venusaur for dead. And everybody knows the best starters to pick in Kanto are either Charmander, so you get an epic Charizard vs. Blastoise showdown, or Venusaur, so you get to witness the glory of Charizard against you.
O.k, that last one's a bit far, but I can't really sum up why...despite others also being awesome, such as Sceptile, Swampert, Feraligatr, Infernape, Empoleon and Samurott, Charizard is truly the best there was, is, or ever will be.
...and this coming from somebody who never watched the anime as a kid and never even played a game with Kanto in until '08...