Al,
The thoughts here are my opinions only.
Both brands produce a great product.
Benchmade:
The axis lock on most Benchmade models is one of the strongest out there.
They use good materials for both blades and handles/scales.
Overall fit and finish is good for a factory piece, though some may say that the early models had off-centered blades and other QC issues.
Price is reasonable.
Emerson:
Liner lock is a reliable locking system (again, you may get various opinions)
Ergonomics are excellent on the pieces I've handled
The Wave is cool (but hard on your pants)
Chisel grind makes cutting straight lines hard for me (righty)
Overall fit and finish is good
I personally do not care for Benchmade in general (even if I own a discontinued model which stays at home). NOT saying they make a bad knife, but just not my cup of tea. Most guys like the 7XX series last I checked.
The only Emerson I own is a 2000 Commander just because I thought the Wave was cool and recurve blade is just wicked. I carry this one in my briefcase.
If you really want to get the scoops on knives, visit Bladeforums, Knifeforums, or UsualSuspectsNetwork.
Aloha