Tips for choosing faction post patch 15

[Slaists]

I'd suggest giving Anthony in IA a try.

The campaign is not as much about the eternal city as it might seem. Anthony starts at war with Parthia and all its satraps while having a good number of client states himself. So, you can have fun beating up the East; holding your line in Greece against Octavian and then, once the East is pacified, turn around to conquer Italy.

Rome actually has the most varied roster in the game due to it's auxiliary system. As Anthony you have easy access to Cretan archers, Rhodean slingers, Syrian armored archers [the best tool against the Easterner horse archer armies], elephants, Persian cavalry (shock and archers) and even Noble Horse (if Galatia betrays him); and that's just the best auxiliary units that come to mind.

You'll want different army compositions when you fight against the Easterners and Rome. In the East you'll rely more on foot missile units to defeat horse skirmishers and archers. In the West, you'll want more Roman infantry and probably the best shock cavalry you can get your hands on. Dacian peltasts are nice against armored Roman opponents as well. I used Illyrian auxilia (stealthy, armor piercing troops) extensively too.

I had fun with Anthony; played to the victory screen without getting bored.

For the Grand Campaign, of the ones you mentioned, probably the most diverse roster is available to Egypt (Seleucids have even more diversity I believe though). Carthage can achieve good roster diversity through hiring lots of mercenaries which are made affordable through the proper techs + dignitaries embedded in armies.

p.s. at some point in my campaign, my client: Judea, grabbed a few regions in Latium... They didn't get to grab the Eternal city though; Octavian managed to push Judea back into the sea.