well i like the romans because they're good for so many different things:
1) They are awesome for rushing (the praetorians guards are deadly)
2) Early gold means that u can put a barracks up early (with ur timber) and send about 3-4 archers (timber and gold) to raid around 4 mins w/o it having any neg effect on ur ability to boom.
3) Wealth is never a problem, so they are good boomers as well. some people will point out that americans get +3 metal, etc for every barracks unit, but thats not an issue when i play with the romans because my economy is always maxed out.
4) With the romans i out boomed the american computer on tougher and annihalted him. And with the romans, i forced armageddon against a toughest American computer (should've won that game, but made a couple of critical mistakes)
but i guess its just whichever nation u're used to. But the main thing is, typically u can tell what a person is going to do when he picks a nation but with the romans, they're good at both rushing and booming, so u don't know what you're gonna get.