Personally, I've done a bit of kung fu and a bit of Tae-Kwon Do. Out of the two, Kung Fu was by far and away the better of the two in terms of fighting and self defence IMO, just because I felt it was more fluid and less static. However, it really does depend on your local school.
The first TKD school I went to was fun because we also got to play with swords (OK, so they were made of foam!) and to try out other things like Ju-Jitsu, but even with the self defence I was taught, I never thought I would be able to fend off an attacker. The second TKD school I went to focused more on personal fitness and again, I don't think I would ever have been able to fend off an attacker.
For me, the kung fu was the best - the techniques suited me well and I loved the mix of tai-chi and kung fu. We also used no external equipment so it was perfect for training at home, although apparently when we got to higher grades we would have been trained in traditional weapons such as swords and sticks. The only difficulty with working wtih partners and not equipment is that you get horrendously bruised (and I recommend Chinese black oil to help!). I once got up one morning after kung fu class to find both forearms entirely black with bruises - it's not a good look, particularly for a girl
I don't know what it's like where you are, but most schools in the UK will let you join one lesson for free, so if you can do this, it might be worth checking out a few local schools to see which suits you best. I really want to take up kung fu again but haven't found anywhere nearby
