Tennis balls affect your game just like strings etc. It's a matter of personal taste. If you like the current balls you are playing with and you perfom, why change? If you want to save some money, buy cans in bulk with friends. It can save you a few bucks and you always have a spare set in case of emergencies.
I used to think Dunlop Fort were the best claycourt balls, but after using Babolat RG Clay court or RG All-court balls, I haven't looked back.