Out of all the grappling martial arts, judo tends to be the one most recommended for self defence. Geoff Thompson, who's a very respected figure in reality based self defence, said he'd put boxing first and judo second, or words to that effect. For someone who really wants to be able to defend themselves when the shit hits the fan, you probably would need some sort of striking background, because if you freeze after taking a punch, no amount of grappling or throwing is going to save you. I wouldn't mind taking up judo or BJJ at some stage.
I have a lot of respect for boxing after taking part in a so called white collar event a few years back. It made me realise that it's not always a good idea to just rush into sparring without learning the technical side of it first. I'm not sure I agree with this whole macho attitude some boxing fans still seem to have though. There have been some really tough grapplers. Just remember how fragile our brains are, and watch yourselves.