Not to ruin anyone's parade but Kizaru should be the one with the lowest bounty among the 3 OG's for one simple reason: he will only act with orders. If he don't have a order to fuck you up, chances are you can escape if you're smart.
Using eggehead as a example, akainu would have killed everyone that he met (including civilians), kuzan would freeze everyone just because its easier and then fought Luffy/zoro.
In terms of danger he is very low on the escale. To the point of being compared with frauds like Fuji.