I like Spyderco better. I have a BM 710-- with the original M2 blade. It's a nice knife, but I have abandoned it since I acquired my Police w CF handle about 6 yrs ago. Spyderco has far more designs and purposes. Their knives are more utilitarian. Plus Benchmade has all those ugly knives with the flame shaped G2 inserts and other sophomoric features.
I'm certainly not sold on BM's quality control being any better than Spyderco's. Spyderco's is superb. I have purchased many of their blades, having given away most of them as gifts. The 710 I own has some fit and finish issues. There is also considerable blade play; if I tighten it up then it becomes too difficult to open. To be fair, I've heard many times BM has improved their quality control considerably.
In summary, Spyderco, IMO, just makes more practical utilitarian knives with a ton of character and superb quality control, especially on their lockbacks, which I love. BM makes a fine knife,too, with their great Axis lock. (Don't care about liner locks on either brand.)
I would like to see BM go back to their roots and make more down to earth, practical, Emersonian designs, while keeping with their improved QC standards.