Well, I'm no expert in this field but I do have personal experience. I would say blued steel ( as far as wear and tear). Stainless will "Gaul" and flake off because it is softer. For example, I have noticed a significant difference in 2 bolt faces of two different Rugers I have owned. One stainless, one blued. The stainless had rounded or "peeled" corners and sharp edges that came from the pounding the bolt takes moving back and forth. The blued one looked almost brand new. I actually had to get Ruger to replace my stainless bolt. The interesting fact was the stainless had only seen standard velocity ammo, where as the blued had seen strictly High velocity Blazers shot through it. Now don't get me wrong, both can last a lifetime. I make sure to keep plenty of oil on my stainless guns ( to prevent gaulling ). But then again I make sure to oil by blued guns ( to prevent rusting ). One final note, if you don't take good care of your guns " cleaning, or riding them and putting them away wet" stainless will take much more abuse, and look better longer.