There are some moves that are really shitty to level (for their next skill). You might not have the required move, to make it "pop". I recommend you cheese the hell out of the game. Drag out the combat by fleeing from the enemies, put the skill on a dash move and use it a few dozen of times (spend a minute or two). The [Scythe] move is one of the best moves for stringing together areal combos (huge hit box in the air, quick, okay damage, good at fixing the enemy in position for follow up moves, and doesn't require much setup other than being in the air), but is otherwise quite useless. You get it from using [Jumping Knee] and [Beam Sword].
[Fisher Strike] is one of those "wonky moves", but it's also a really quick move (in an areal combo) and it deals a lot of damage.
I recommend you wait till a move gets to lvl 2, if you are uncertain whether to use it or not in your combo. A lvl 3 body blow will deal around the same damage as some of the later skills when they are level 1. They will eclipse body blow in terms of damage, once they get their first level up (lvl 2). Moves also tends to get a bigger hit box, faster execution, and lower heat cost, as they level besides the damage increase.
The enemies have hit boxes, but they also seem to have "weight". Meaning they react differently with knockback, in the air, and being knocked down depending on their model. Some combos you have strung together against the test dummy, might not work at all in real combat. I always felt, the combos that suffered from this, had this air of flimsiness over them, when I tested them. Like combos with [Magnum Uppercut] that barely manages to hit the tip of the foot of the enemies.
Viability should be of major consideration. Being able to do 2k damage doesn't mean much, if you are only able to land it 10% of the times. The big fancy moves looks cool, but having a combo bar with them is probably not all too functional/effective. You need the meat and the potatoes of the combo, before you consider the more flamboyant stuff.
Flexibility is also important, but not as much as viability. Switching up at the right place and time not only makes you faster and more effective (increasing dps). You will probably also have more fun playing the game this way. Instead of being locked away at a very specific combo move, making your mech feel more like a clunky tank.
Speed and damage. You need to damage the enemies in order to defeat them. Having a move that takes several seconds to execute with a tiny hitbox dealing a great amount of damage. Isn't nearly as good as 2 consecutive moves that deals the same or more damage in a fraction of the time of the big move. Many of the fast moves also offers mobility, making you take much less damage. The long setup move, will have the enemy use you as a sandbag for the duration and it's just not fun (for me at least). You also risk being knocked down, knocked into the air, or shocked, while trying to execute the big move. The speed of the move should not only be considered for you dps, your defence will also improve.