I guess having an idea of what you intend to do with the knives would help us help you.
Given those choices, I'd pass on the Ontario SP-4 due to it's low grind and presumed obtuse edge. I like SOG, but I've never purchased the SEAL Pup because of the serrations. I do like the SEAL Pup Elite because it is available with a plain edge. If SOG were to make the SEAL line with plain edges, I'd buy on of each.
Of your choices, I'd pick the Short Kabar, with a plain edge. And I'd grind off the top guard as soon as I got home. The 1095 steel is easy to reprofile should you find the need, and it is easy to touch up in the field. It is a good and basic utility knife.