I'm up for anything at this point. (For his powers and his default costume.)
But mine would probably would be for him to be Bleeding Edge.
Bleeding Edge: This armor made Iron Man the most powerful hero in the world. It can go toe to toe with Thor and savagely beat an amped Red Hulk. Its power source has been described as a man made star. This entire armor is kept inside Tony's body until mentally commanded, at which point it manifests itself as the Iron Man Armor. The armor is made up of Nano-Machines that can now be commanded to turn into any type of structure upon Stark's skin. For example, the Nano-machines can turn into clothes, other armors, or even different beings completely, by having the Nano-machines change their properties into whatever Stark wants them to be. It can also dissociate to transform into the Iron Man armor whenever Stark wishes. The armor and Stark's own transhuman body are powered by the high-yield R.T. node mounted in his chest. The high output of the node has greatly augmented Stark's intelligence and provided him with superhuman-level multitasking and learning capabilities.
His Sig would be some version of the cannon that this armor can create by itself.
Other suits that do not have cannons for palms and cannot create cannons over palms would just summon this instead.
Unibeam could be a massive burst damage power that you hold down, and gives you damage reduction.
*Cough need a better power tree *Cough that's what matters most *Cough.
But that's just a version of Iron Man I really want to see.
To blow stuff up without using missiles.
Missiles is Rhodes's thing.
Now it's your turn to show what you want Iron man to be!