Pocket Battles, which to get?

So the Pocket Battle games have been reprinted, and I'd like to try at least one. You've got Macedonians vs Persians, Romans vs. Celts, Elves vs Orcs, and the newest one, Confederates vs Union. Question is, which one should I get? Are there any improvements or rule changes to the newer releases, or are they basically all the same and I should just buy whichever one appeals to me the most?

The rules had not changed when Macs and Persians came out, but they had been rewritten. My guess is that the reprints all have the revised rules, but I don't know that for sure. We managed to play Celts and Romans with the original rules just fine.

S.