Unless you want to spend a ton of money, the factory shock is the way to go. Many aftermarket coil overs available, but they start at approximately 300 dollars per wheel! I'm still using my factory suspension after many other modifications, just can't bring myself to spend that kind of money!
This is like everything else! Somewhere down the road I may look at aftermarket suspension, but I get turned off when I see the high prices involved. So far the stock suspension has met my needs! No cheap way out here!
When I broke a shock I looked for a aftermarket that would match the stock shock at all the local parts stores and nobody could come up with one. NAPA even tried to find a motorcycle shock that might fit.