If the person trying to do you harm is already within arms reach then a gun isn't necessarily the best option. That said I personally don't see the need to carry a baton, but it's really up to the individual on how they wish to arm themselves regardless of legal convolutions.
If you have to have a baton, the Monandock's are great.
If you carry the baton on you, be prepared to get hemmed up if caught, unless you are a LEO, a correctional officer on official duty or military.
The baton is a great tool, when employed properly, which does require more technique then simply swinging it wildly at an attacker. For instance, in LE, we are trained, very specifically, areas to target. Also, it is simply too easy to escalate the use of a baton from non-lethal defense to lethal, by striking in specific areas. Anyone that has been in a fist fight and intended to punch someone square in the nose but, accidentally connected with the opposers forehead, in turn injuring your fist in the process, knows how easy it is to not land the blows you intend.
My suggestion would be to carry your pistol for personal defense. If you are concerned about dogs, or over penetration, or close in encounters, or any other myriad of excuses to carry an expandable baton, may be consider more firearms training, reconsider your weapon/ caliber choice, and if you truly feel it's necessary to add another "tool to your tool box", consider investing in some sort of "hand to hand" training...
Or, go old school and carry a 3 cell maglight.
