Well, the 225/50s are a slight bit closer in size to the OEM size, and since it's taller, it'll fill out the wheel gaps more than the 45s, as well as offer a smoother ride.
As for handling, IMO it's more the type of tire (brand, performance category, load and speed rating) that makes a difference compared to the size.
As for handling, IMO it's more the type of tire (brand, performance category, load and speed rating) that makes a difference compared to the size.