25 different posters will give you 25 different opinions. Any name brand, forged slide will work as well as the other. What is wrong with the pistols present slide? There are a ton of aftermarket "bells and whistles" out there. Its just a matter of what appeals to you, and how much you want to spend. With the exception of new springs, or a tuned ejector, for example, most aftermarket parts work no better then stock.
Larry