The AS is much more fun to play as because there is much more challenge. You'll have to fend off attack after attack from all sides. Plus, you get some really cool late game units. Playing as the Yellow Death is just boring with little challenge.

Although all the challenge goes out of the AS if you simply demolish a bunch of wonders to get tons of money on the first turn and use that to cripple the Ptolemies within 10 years.