I will sound like a broken record, but i find that TKD ITF (at least at my school) has a good mentality for semi contact. You don't have the low kicks, but if you cross train, you will get plenty of other benefits.
And you can still kick hard. It's usually the punches to the head that are expected to be semi contact. But since it's more about speed than power, the sparring can be very competitive, but without the body abuse of KK or MT, and without the head abuse of KB and Boxing...
At least that's my opinion from my personal experience.
Been to lots of MT gyms, but only one TKD, so i may be wrong. But from discussions, and what i can see from tournaments etc, I thing it's pretty much the same mentality.