Personally I have always wanted to see armies based on the rise of Rome in 15mm, Gauls, Oscans, Samnites, Campanians, Etruscans, Romans, and Magna Grecia, no ones really doing it properly with complete armies that I've seen (happy to be corrected), or the sculpts are too small or too big and don't match any other supplier further limiting there ranges. the period I would like to see is about when Rome switched over to a manipular style of fighting, so some nations were still using the older hoplite formations and as mentioned before some the manipular formations and others still using the good ole fashion barbarian Horde attacks, I think this would be an interesting period in history to wargame.