I currently have Samsung SII with Sprint(Unlimited data). I like it to some extent as it has less crashes than the previous Samsung phone I had. The battery though, drains right in front of my eyes, whenever I open any application(Fidelity trading app is one example). For example, if I open the app, i can see the battery strength drop from 85 to 80 within 2 mins.
My wife has a blackberry which is past the 2 year contract. She has her eyes on the SIII , while i have been telling her to use the Iphone 5. Her primary use will be corporate email/calendar and possibly search and maps.
Does her company have Mobility Messaging available? An example is Good Technologies app, This is the question to be answered for replacing the BB. If her company doen't have Mobility Messaging(MM), then wait. If they have MM then verify if the app is available for both phones.
I have the iPhone 5 with Good. I am very happy, and the phone works very well. I have the latest version of iOS (6.1). Test both phones and go with what you like. Our whole department have migrated to the iPhone 5. No issues.
I got the S3 and wont go back to apple untill they get a bigger screen. S3 battery life is amazing, having apps open and refreshing all the time with trading and the battery will still last me over 24 hours unplugged easy.