1. Flame is situational, and I have yet to figure out the situation that something else the MEC does isn't better. Fist however increases movement range (ummm... OP? Yes!) and after the fist upgrade does enough damage to almost one hit anything in the game with literally 100% accuracy- once again, NO RNG here... Easy choice for the OP!

2. Same as the mines for usefulness- synergy with mines from second MEC is off the hook useful (one mines the other shots a grenade and sets off mine). Healing mist is weak. Easy choice.

3. Electrical pulse hugely situational and ineffective at best even in those situations. 5 mines? Unreal useful (removing cover for sniper to "in the zone") in a million situations. Can also be used to cheese the strongest enemies in the game (spam them on them from out of sight) No-brainer choice.