I'm a fan of both.
Yes, at lower end price points Spyderco's do have a slight edge over Benchmade. Overseas labor is cheaper, and that is reflected in the prices on their knives. However, at the higher price points these differences largely disappear--regardless of where the knife is made. For example, the Sage 2 is just as expensive, if not more so, than many of the Benchmade blue class knives. I really love my 943, as well as my Sage 2, but the Sage 2 is about $20-30 more expensive. Likewise, the 710 is about $10-15 cheaper than a Military.
Some of the Spyderco knives are, to me, ugly as sin. But, then, so too is entirety of the new 2010 Benchmade lineup. But, I'm loving the 2010 Spydercos.
It all comes down to preference. I honestly doubt that a quality knife from either company would fail under any reasonable - and even some unreasonable - use.
But hey, I'm just a 22 year old grad student.