With Huns you don't have to build houses, get cheap cavalry archers and faster working stables.
Pick Japanese, big ecnomy bonus on the water :O
Pick Celts, Woad raiders are awesmoe
Pick Persians, your town center works faster
Pick Britons, you have the ultimate shepherds!
Pick Aztecs, you have +5 carrying and a bug that causes them to farm faster
Pick Mayans, you have 20% longer lasting resources (120 wood from tree instead of 100)
Pick Saracens, you can balance out a bad economy at the market. For the skilled player, the market can be turned into a substitute for a fast castle at 13 minutes and go on a rampage of his choice (Monks suggested)
Pick Teutons, cheap farms and your town center sees a lot of your starting resources.
Pick Mongols, your scout is way better at scouting.
Pick Vikings, cheap docks and early wheelbarrow and hand carts give you a big economy boost.