For general purpose bushcraft use I would go with the Ritter RSK Mk3 from your selected 4 options. A slightly larger blade might be required if you are going to chop branches and cut wood though, something like a FÄLLKNIVEN KNIVES - S1 FOREST KNIFE maybe better suited in a VG10 Laminate Steel with a 5 inch blade. Have seen it for about $109 with a leather cover and should be within your budget from your initial selection. VG10 and CMP-S30V are both top notch steels but the VG10 Laminate steel may have an edge on the CMP-S30V over its resistance to reported possible edge chipping (this is most likely to heat treatment issues from other manufacturers, therefore would not be an issue with the Ritter RSK Mk3). The Swamprat Howling Rat is not made from a Stainless Steel and will have good/excellent edge retention and excellent toughness qualities but poorer corrosion properties (important to retain an edge in a corrosive environment i.e salt water)