A favor...

[PsychoTechFreak]

More abilities to finetune the AI. Something like scripted events. For example, if you encounter this schemer race then replace everything from research slot #2 on with counter intel. Or if you count more than 10 mines, focus on minesweeping. Scriptable special attacks like planet invasions, blockades.

Programming the AI could be more user-friendly and intuitive.

More than 255 Systems maps.

Better AI use of training facilities and other planet-wide facilities. Or change them to system-wide if the AI is unwilling to park their fleets over training facilities (and similar facs).

[dumbluck]

I'm surprises Fyron or SJ haven't spoken up. they have modded enough to know most of the guts of this game.

One that comes to mind is ship/fleet experience. ATM it is completely hard-coded. Being able to mod what happens at what experience level would be very nice.