It all comes to tastes. For me, there's no doubt that the best Fire Type Starter is Blaziken hahahaha, Joke. Is not, It is Charizard. Having balanced stats and a decent speed. If from far the best partner one can ever get. Access to two Mega Evolutions, X and Y. Y, while being lower in Atk. has a great Sp. Atk, and it hits really hard on Sun weather, which is summoned by its ability. As for X, I love it, finally earning the so-wished Dragon Type, Dragon Claw and Flare Blitz are threatful alongside Tough Claws, this while not boosting them with Dragon Dance, acces to Thunderpunch to surprise water type. Earthquake, Brick Break, and many other usabel moves. This in-game, while in animated series, be it Movie, Ovas, Origins, Especials and the anime itself. I haven't seen another pokemon able to face Legendary Pokemon (Rayquaza, Kyogre, Groudon, Articuno, Entei) by itself as well many others Mega Evolved pokemon and being victorious. Also, participant in many other main battles (Blaziken, Greninja)
Maybe I'm overated it, but it's my favorite since I was child. Probably is guilty for my like to play pokemon games. But that's it. I'm not saying Incineroar or Blaziken are bad, no. they're really good, I run then in several playthough I have. But Charizard takes the spot.
EDIT: I guess I slipped off the topic, sorry.