egypt... income plus income plus ... money money money... XD
If you want to make money, you should consider Inca or Arabia instead of Egypt. Burial Tomb's lack of maintenance cost is barely an income plus.
Also, Songhai if you want to play aggressively - Barbarians can bring in a lot of cash.
also Persia. you can consistently stay in a golden age with them if you get and/or time the appropriate wonders/policies. My largest non-military gpt was in a Persia game (on Emperor). It was totally fun to see +80-100 hpt and 300+ gpt in the same game. I easily could have bought my diplo votes if i hadnt gone science.
not only do Songhai get the barbarian bonus, and a bonus for cities (assisted by having the game's only cavalry unit that doesn't suffer a penalty against cities)
Upgrade chu-ko-nu to rifles don't double attack, do they?