I was going to change my first post but decided nah. Anyway

MCH
Dismantle - I want this back give MCH back a bit of it's old utility.

Flamethrower - Rework it, I don't know what would be the best way to rework that makes it feel great to use but personally I'd be good with it being a ground targeted aoe that summons a turret that just spins around with it's flamethrower. This way you plop it down and continue with your rotation. Another option would be for it to interact with Bioblaster, like if the enemy is afflicted by Bioblaster Flamethrower deals a higher potency. Make the potency high enough that even on single targets BioFlame would be best but this doesn't solve the issue of Flame requiring you to be stationary.

Battery building ability - I'd like to see something to helps us build battery faster. The simplest solution would be be an instant X amount of battery or a double current battery ability but that sounds boring. I would like it to be a either be a self buff that boosts your dps as well as let you build battery from every weaponskill or a buff for a party member that boosts their dps and build battery for you.

Wildfire - Wildfire needs a rework. In HW and StB Wildfire was your big burst. It was what you looked forward to and worked toward but now it's just a button you use with Heat Blast/Crossbow spam. It still important when it up but it doesn't feel rewarding when you see Drill and Airanchor dealing similar numbers.

Battery/Heat Gauge - one of these needs a more use. Heat would make the most sense since it the one we build up the fastest. They could put Hypercharge on a 60s cooldown leaving you with excess Heat that you could be spending on other abilities. Another option would be for Battery to get more use instead of just Queen. Queen could be on a 60s or higher cooldown and use a flat 50 gauge meaning you will have excess Battery to spend. This Battery could be used to summon Rook who could be independent from queen or they could give us a new battery dump ability or both.

Expanded Combo - This will probably not be everyone cup of tea but I'd like to see MCH's 123 combo get expanded upon. I personally would like to see Slug Shot and Clean Shot both be able to proc additinal Weaponskills like DNC, so essentially making our 123 into a 12345, 1234 or 1235 just to hell give the job more variety.

Overall I can't see all theses things working well together but I would like to see some of these to help make the job have more variety.