In the attachment circled in red is where you could put : "Greater than", "Less than", "Equal to", and "This".
The first selected would use one of the first three then the second selection would use "This"
So when checking distance from closest enemy they could choose greater than. Then when selecting what to check again ie. Distance to closest ally base they would choose "this"
It would look something like, Distance from closest enemy Greater than distance from ally
both distance / health / shield etc would still be check from the chosen target at the beginning.
This would make the game much more in depth while cutting out;
1: the amount of nodes
2: time spent making
3: the limitation of only 3 distance types(even if still kept)
4: amount of nodes and trees
5: time spent running through
6: space used
And of course overall ugliness of ai.