For what it's worth, in BES 4.1 during an upgrade or installation (can't remember), it goes in this order:
Code:
Dispatcher
MDS Connection
Policy
Attachment
Sync
Controller
Router
Server Alert
Collab
Instant
To note, RIM's documentation for High Availability gives the 'net start' commands in alphabetical order. So I suppose that could be the definitive answer you're looking for, even though the level of expertise in this thread should have been more than sufficient (atleast from where I'm standing).
P.S. - I *fully* agree with what dev put in his last reply. You asked what order the BES services start and then rambled on that there must be an order and specifically pointed out Exchange and SQL services as dependencies. Not really what you originally asked for, no?