Both have there advantages and disadvantages, BBM Android let you have access to a blackberry id which is attached to your email and linked to a pin, that means your contacts and chat history, profile, will be synchronized when ever you logged in to any Android device, it even synchronises your BBM profile from your Blackberry phone to Android. you can have different BBM pin one for your business, or any organisation and one for yourself. can share your pin to individuals,business contact id,i think it is More secure sharing your pin rather than your mobile number. Whatsapp in the other hand makes use of contacts in your phonebook, you will be hidden from people without your number in their contact list and they will be showing in ur chat list. you only share your mobile no to people which is not secure because you may not want to give everybody your no, the chatting platform makes more sense than BBM Android, let's see how their update will be, sending of files are compressed and send faster than BBM, But both run in background, can send messages with data connection but will be delivered on data connection. what do you think guys?