I cannot recommend Cold Steel, CRKT, or SOG. They are not bad, but I feel there are much better companies out there for the same money.
Two very popular knives that fit your size range and price are the Spyderco Endura and Benchmade Griptilian. They are both fantastic. The Endura may cut a little better, and the Griptilian is easier to open and close thanks to the Axis lock.
If you decide you do want assisted opening, I recommend either of the two budget Spec Bumps. There is the Speed Bump and the Spec/Speed Bump. The Speed Bump is cheaper and has rubber-esque scales. The Spec/Speed Bump has G-10 scales just like the real Spec Bump. They both have Sandvik steel instead of the S30V on the Spec Bump (or CPM154 on the older Spec Bumps).
If you decide to go a little more expensive, I recommend any of these (all fantastic):
Spyderco Manix
Spyderco Military
Benchmade 710
Kershaw Spec Bump
Al Mar SERE 2000
Masters of Defense ATFK
Emerson Commander
Emerson CQC7