My son has had iphone 4 and iphone 4s. Has just got a galaxy 3 and loves it, says it's far better than the iphone. Had no problem transferring stuff over but I don't know the details.
I would go for the Apple IPhone 5....reason being never had any real trouble with it, or the 4s also, apart from when I dropped it and cracked the case..... an Apple Store very near me..... after sales customer service really excellent, friendly and helpful staff and efficient.....paid a small fee ... and got a brand new set and no reciept needed as they have ALL the details on their system due to the Serial No of the phone.
Samsung's are good too though....so personal choice imo :)