Code Geass: Hangyaku no Lelouch, Accel World Recommendations
Though these two Sunrise series have greatly different settings, there are many surprisingly recurrent themes:
A physically weak male lead who gains the power to create their ideal world.
A contract with a mysterious girl with a potential hidden agenda.
Strong production values and intelligent action.
Most importantly of all, high entertainment value!
Why?Because the Black King will reign supreme in both anime :D