For Exchange integration, you can't beat BB. To even be usable, you are going to have to purchase Touchdown in the Market.
Shame really that Google has not addressed this. 95% of the corporate world is on Exchange, and will NEVER switch to GMail. Many enterprises specifically ban Androids because of the lack of security and policy management. If they would integrate with Exchange (which they could if they wanted to) they could bury RIM, but as it stands now, Android is going to continue to be more of a consumer device.