The thing is, Magmar does get a better spedef because eviolite, it can will-o-wisp, and doesnt have to use moveslots with HealBellStealthRockWish Shenanigans. The reason to run Magmar > Flareon is generally because flareon's movepool is rather gloomy and needs and upgrade. It's arguably better at the job, sure, but that's not the point. Charizard get SD/BD and quite a of Magmar's aforementioned moves, yet gets no comparison (Weak to rocks. Cool. Has flying type. Cool again.)
Camerupt, however, is also a good argument. But it certainly can't take Surfs as well, and doesn't even resist ground (though being neutral to rock is pretty cool).
Magmar is better offensively, that's okay. But if you don't venture to see what else it can do, then you'll never really know. Bulky attacker is prolly common, but most certainly the best.
Try the set, fail, then tell me :3