AMDRadeonHD :
MC_K7 :
Even with a SSD, there's no real impact on gaming since the hard drive is not involved during the game. The only difference it can make is load the game or load a map faster. But once the game is started pretty much everything happens between these 3 components: CPU, RAM and GPU.
But between the two, I would go with the Black. I heard that the Blue have higher failure rate. But in term of performance, there's not much difference between Black and Blue. The Blacks can be a little noisier though.
That's what's important for me, loading times. I've had experience with my old Western Digital Caviar Blue 640GB, it actually lasted 5 years
and I've got to tell you that year after year it lost about 5% of the performance, so it lost about 25% after 5 years and it would even last longer if my PC wasn't too much abused with gaming (It died finally, it had HD 4350 512MB DDR2, Pentium E6300 2.8GHz and 4GB DDR2).
Get a SSD then if you want fast load time.
Also, even with a mechanical drive you shouldn't get degradation over the years. It will happen if you keep copying new files without doing clean-ups and without defragmenting periodically. If the drive gets too full, of course performance will decrease, this is why you need to move files elsewhere (external drive for instance).
Also note that if you get a SSD you should disable defragmentation (it doesn't affect SSD).