CTD removal is probably the biggest one.

But I'd like to see the 'C's replaced with 'K's in from maps and Faction graphics for Hellenikoi factions (for example, Arche Seleukeia -> Arkhe Seleukeia), as well as from the text files (although these I can alter myself). The same applies with 'U's and 'V's for the Romani. Finally, as some others have said, I would tone down the AI Money Script and/or find further means to make blockades and economic warfare more painful and effective against the AI.