In my current Makedonian campaign I got bored of doing the hammer and anvil all the time so I recruited a full stack of horse archers from the Crimea and have that fighting of all those Ptolemaioi fullstacks. They suffer minimal casualties, but every once in a while i have them retrained.
Otherwise I went to conquer Krete for it's archers, antiocheia for it's syrian archers, the crimea for their nice heavy archers, scytian units and Thrace and that city on the amber route for it's great 'barbarian' units.
If possible I want a unit of rompadoroi (or whatever) with my army, they chop through everything!