strong is the same as retain in a property declaration so for ARC projects use strong instead of retain.
Use assign for C primitive properties and weak for weak references to Objective-C objects.
and more here: http://developer.apple.com/library/ios/#releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
However, note that assign is the default. So, for an int you would use:
@property (nonatomic) int value; // assign by default