Very cool game! My favorite mecha build so far uses Omega (armor), Excalibur (weapon), and Rhino (wings). This is a melee-oriented build which uses physical ramming to kill as many things as possible, shooting only at bosses, battleships and blade mechas.
Rhino boosts energy upon each melee kill, building up the Core superweapon. I like to use the Archer core, which is almost never useless, but there are other options, Tremor is also interesting since ground units have a tendency to explode on contact, making melee a dangerous option even with Excalibur.
Omega is used because of the shield regeneration boost. Since this build is shooting very rarely, shields regenerate almost all the time, reducing the threat of enemy fire.
I would also like to report a glitch in the game. If you get to the fifth boss and destroy a battleship, you will win the game without killing the real boss. This issue should be resolved... Apart from that, it's a very cool game.