Flamethrower definitely needs looking at, I don't mind the channelling itself, but I would give it synergy with Bio Blaster since they line up and it would give the ability more impact. I would also consider halving the duration, doubling the damage and maybe giving it the "Suzaku Kick" treatment, where you can push it again to get off a finishing blast. Flamethrower has the potential to be a highlight of MCHs AoE suite, they just need to give it some attention and have it synergize with the kit instead of being this strange skill that's just barely a gain over just using Scattershot.

As for Queen, they should really look at that AI, its a pain when you can hardly control where it goes, also the long summoning time can make it a pain to get it to fit in burst windows properly, I like Queen but it could use some work.

As for Wildfire, I'm not really sure what to do with this one, I definitely think it should have the potential to direct/crit and be AoE (like in PvP) I'd also say Air Anchor would be a good fit for AoE simply because the animation lends itself to it. You would need appropriate drop-off of course, but this would go a long way to improving MCHs AoE game.

Overall, I still enjoy MCH, but those are fairly easy areas where they could make positive adjustments.