I suggest the Spyderco Military model for a primary tool purpose and the Microtech SOCOM Elite-M model for a primary self defense purpose.
Spyderco Military
Specs:
Blade Steel: CPM(T) 440V
Blade Thickness: 5/32", 4mm
Clip: Stainless steel/black
Diam. Blade Hole 9/16", 14mm
Edge Type: PlainEdge, SpyderEdge
Handle Material: G-10
Length Blade: 4", 102mm
Length Closed: 5 1/2", 139mm
Length Overall: 9 1/2", 242mm
Weight: 4oz, 113g
Microtech SOCOM Elite-M
Specs:
Blade: 154CM stainless steel, hardened to 60 RC
Blade Length: 4.05"
Thickness: .174"
Open: 9.11"
Closed: 5.1"
Handle: 6061-T6 Aluminum Hard Coat Anodized
Lock Mechanism: Manual Action-Constant Thrust Load With Wave Spring, 154CM MICROBAR® Lock
Weight: 5.6 oz