Although I agree those benefits are all strong, I actually think they balance out over the course of a game. 500g per wonder is powerful if you find a few wonders in the first 30 turns, but after that it's actually fairly weak in my opinion.
Strong units are good, but without a good science output, production or culture, you lack strong foundations back at "home".
The early science for Babylon is (in my opinion) one of the stronger benefits, but doesn't always equate to someone running away in science.
Personally I prefer other leaders and have always coped well against the above listed countries.
I am speaking in terms of good players of equal skill levels. If both players know how to utilize their civs properly and are of equal skill, the person with one of these civs will dominate the other equally skilled person. Having no trouble with a bad player who plays one of these civs is not evidence of them being balanced. This game is not balanced, the developers don't care very much if it is balanced. This is not Starcraft. Most competitive games require many rules to ensure a fair and balanced match. If the game were balanced competitive games would not require any rules such as no great wall, no terracotta, no _+100 gold faith, +4 faith from NW etc.. Spain is the most universally banned civ in competitive play.