im guessing you're wanting for us to write a dialogue on a roman and a greek discussing their form of government? a traditional democracy had it were all citizens voted on eveything (not that all citizens did)
in rome's republic the people were represented, like the people of america are represented now, by senators. these senetors ruled for life. I would argue, on the side of a democracy, that having a democracy better ensures the peoples representation in government. but also take into consideration that communication was very primitive back then, which could cause problems for a democracy ruling a larger country than greece (not even the city-states in greece were considered there own seperate powers)
hope this hepls!