On EB there aren't large margins as gearing up AI even more would require extensive redesign.
If you made a mod from scratch you could use a combination of religion and the senate mechanism to make some factions more bloodthirsty towards each other, with a moderate use of factional objectives to focus it better.

You might also want to take a look at the XGM mod family (XGM, XC and DTW) to see their use of special buildings to give faction-wide bonuses rather than using cash infusions from the script.
As for choice of exe I'll always stay partial to the BI one as I worked for years on its features and it allowed me to pull off some pretty good tricks.