I've noticed the ease at which some people can donate massive amounts of Exotic Matter to the base and then end up taking the lions share of a resource percentage.

my suggestion is this.

the first pip on a given research tier that is required for donating to a base allows you to contribute Complex Tech Parts, the second pip allows Energy to be donated, and the third allows Exotic Matter to be donated.

Additionally I think considering the rarity of Complex Tech Parts in comparison to other resources donated to a base perhaps an experience reward could be given out that is perhaps double that of a normal Energy contribution.

This has all been suggested before.

What about those of us that have set things up a specific way based on current values.

My legion has it to where no player can donate more EM than the sum of their energy and Tech part contributions. This rule in my legion is heavily enforced and breaking will and has resulted in members being kicked.