I only played rome the last game. The game before I was assigned asoka and achieved a 59,000 point diplomatic win in the year 1622. All games are on standard maps at marathon speed. I wish someone besides augustus had the cre/org trait combo. Prats really do imbalance the game, but as I am not much of a warmonger I think the traits are more important. If I had been more blood thirsty I probably could have finished off most of my rivals long before I did.
so maybe you're ready for monarch

.
My personnal experience was :
- noble has always been easy, never lost at this level. I played it for a few games, just to get the feeling for the new game mechanics.
- prince was hard at first. lost many games, before looking for better advice here on the forum. After checking hendrickszon's GotM 2 spoiler, prince got suddenly very easy

. Never lost a prince game after that. I still played a dozen or so of those games, with various leaders and maps, because I lacked confidence to go up.
- when it was obvious I wouldn't lose a prince game, I tried monarch. I started with a cultural game, those I'm most comfortable with. I had to replay the same game a few times, but I made it. So you could say I lost 3/4 monarch games, before getting accustomed to the level. I didn't lose any monarch game on vanilla after that. But when warlords came out, I won "easily" (afterwards, I realized it was closer than I thought) my first monarch game, then lost a bunch of games where I tried some exotic moves. Now, I'm pretty comfortable (90% odds I win any monarch game I start) at this level.
- I tried a few emperor games, won some (cultural game or domination playing rome

), lost some (well, not really. I gave up on a few where I had a few unlucky starts, like constantly (!) losing with egyptian war chariots against zulu chariots). I think I'm at this level now, if I try hard enough.