Is Blaziken a better fire attacker than Charizard?

Charizard is better against bug and grass
Blaziken is better against ice and steel

Blaziken has somewhat higher attack than Charizard with a fair bit lower bulk. Probably pretty situational which would be better but I agree that Blaziken is worth a mention if Charizard is.

Flareon is like the best of both, almost Charizard's bulk, higher atk than Blaziken.

The top choices are listed if they are on the DPS-TDO efficient frontier; i.e., a Pokemon won't be listed if in every matchup there is a strictly better (non-Legendary) choice.

When fighting Grass-types and Bug-types, Charizard has higher TDO than Flareon and that's the sole reason why it got picked. In Blaziken's case, however, Flareon is always the better choice, therefore Blaziken did not make the cut. That said, it is definitely viable.

Counter is superior to Fire Spin, and Overheat is somewhat superior to Focus Blast, so Blaziken shines in matchups that also allow it to make use of its Fighting typing.

This'll be more apparent during future raids against Regice and Registeel.