I'm also loving the "swastika guys" (Samnites Milites). I use them as a heavy skirmisher unit: they can trade javelins with anything, take down marauding cavalry with their spears, and in a pinch can serve in the main battle line. They’ve got a high upkeep, but I use them in place of equally-expensive Triarii in my Italic legions (which consist of Italic Hastati, Italic Principes, and Samnite Milites).
For heavy cavalry, I'm getting a lot of use out of Equites Campani from Capua, which are described in the game as "probably the best cavalry in Italy". These beauties have a decent charge combined with good melee attack and defense, so you don't need to constantly pull them out and reform. All that, plus they throw javelins and have great stamina. Two thumbs up. 
What I miss are decent missile units. I'm only 12 years into my campaign, but I don't want to have to fall back on Funditores – where can I find some good missile troops to go up against the Keltoi Archers and Slingers? I'm even thinking of a quick trip to Corsica or Sardinia, just to see if I there are any mercenary Balearic Slingers for hire!