The only thing that BES does better than Activesync is the folder replication.
With Blackberry Enterprise Server all of your folders get replicated to the phone... So, if you have a folder from let's say Ron Avidan, and all of your email from his email address goes in there... It always gets replicated and you are notified.
If you use Activesync (iPhone, HTC) then only your inbox is replicated and pushed constantly... If you open a folder for email, such as the Ron Avidan folder, then it will sync that folder when you go look at it, but it won't do it behind the scenes or notify you.
However, if you're an enterprise customer and you like android devices instead of blackberry's I recommend "Good Technology".
It basically does what BES does for blackberry on damn near anything else... We used to use it for Palm devices... It is a FANTASTIC product.
For the IT nerds... check it out here:
http://www.good.com/products/good-for-enterprise.php