I've never had much of an opinion about any of these three Pokémon in the past, but I have recently built a team that includes an all-out attacking Blaziken, and after using that team in a good number of battles, Blaziken has definitely become my favorite of the three fully-evolved Fire/Fighting-type Pokémon, as this Pokémon can be incredibly destructive with its Flare Blitz, Hi Jump Kick, Night Slash and Stone Edge attacks, allowing it to hit pretty much every Pokémon in existence with at least either a neutral hit from its incredibly powerful Flare Blitz or Hi Jump Kick, or a super effective Night Slash or Stone Edge, backed up by its very high Attack stat. It is also an incredibly fun Pokémon to use in my opinion, especially when I switch it into a Ferrathorn, a Choice Scarf Genesect locked into Ice Beam or another Pokémon which cannot threaten it much, and then I fire a Hi Jump Kick or a Stone Edge as my opponent switches either to a Pokémon which resists Fire-type moves, only to watch as that Pokémon loses a large amount of its health if not get taken out instantly, while my Blaziken acquires a Speed Boost in the process, using the turn in which the opponent switched their Pokémon out to do two things at the same time. Equally fun is when I send Blaziken in against something it is normally slower than, but would be faster than after one Speed Boost, and then fire an attack as the opponent switches to a Pokémon which would be faster than Blaziken after a Speed Boost, such as an Excadrill in a Sandstorm or a Kingdra in the rain, thinking I was going to use Protect on the turn in which they switched, only to have their fast sweeper taken out by an unexpected attack on the switch. As such, Blaziken is easily the most useful of the three Pokémon mentioned in the title of this topic in my opinion. In fact, I'd say it is overall one of the most useful non-legendary Pokémon in existence.