In order from greatest to least:
Quilava
Quilava has always been my favorite mid-stage evolution of all the fire starters. It also ranks higher than a lot of other mid-stage evolutions amongst all the starters for me. I don't know what it is particularly about Quilava that makes me favorite it more, perhaps its cool design; maybe it's the fire that burst out of its back; probably because of how nicely it's portrayed in the anime; whatever reason, I've always favored it. To be perfectly honest, I actually like Quilava more than Typhlosion.
Combusken
Coming from my favorite region and generation, Combusken probably places second because of the anime. May's Combusken had great personality, even as a Torchic, and it performed well, both performance-wise and competitively, plenty of times. Not to mention it's the first Fire / Fighting Pokémon, and after it, GameFreak just overdid it with that type combination later on.
Monferno
Okay, I really like Monferno's design. At first, I was turned off by it, but as I finally used it as my own starter choice once in a restart of Diamond and Platinum, it grew onto me. It grew onto me so much that I refused to evolve it into Infernape. Fun little fact for you, it's been about a year and half now and I still have it.
Charmeleon
Eh, the Charmander line has never been my favorite starter choice to be perfectly honest. I mean, it's a very cool Pokémon, but I feel like it's way overrated these days ─ especially Charizard. Not to mention, like most of the original 150 Pokémon, it has become too much of a simple design for me now.
Pignite
Oh dear lord, I don't know how many times I've said it before, but if I ever choose Tepig as my starter, I'm not evolving it. I just don't like Pignite all that much design-wise, and Emboar in my opinion is much worse. Hence, it's last place on my list of favorite mid-state Fire starters, and unlike Quilava it places much lower in the charts compared with all mid-stage starter evolutions. Surprisingly, the anime doesn't help me like it much more either.
...and totally irrelevant, but the art used for the flames of the image you used for Charmeleon, Quilava, and Monferno are awesome!