I think it depends on how the class is taught, if it is strictly a self defence class then technique could well be the focus but if its a class which trains fighters conditioning will be high on the list and I believe the training done by people preparing to fight is second to none.

But generally I do a lot of sprints, intervals and ciruits at the track and squeeze in little 20 min strength or ab workouts through the day.

If it is meant to be mainly for fitness kickboxing is good as its fun, practical and you uses the upper and lower body equally.

Things like jujitsu will have you being thrown about, some people arent too fond of the break falls or the fact that you may be spending periods of time in between another persons legs!

I think you just have to look into whats local to you and find something you enjoy. Also think carefully about what you want from if as some 'schools' can get expensive because you have to buy uniform, pay for lessons, pay for gradings to achieve belts etc. Most schools should allow you to do a few lessons before you commit to buying any uniform etc so I would say try a couple places out first.