Have a look at Wing Chun Kung Fu. Amazingly complicated and deep. Every move is defence and attack at the same time using minimum energy, quite relevant nowadays.
- Taekwondo (and karate styles) - do them if you're in it for sport factor. They are mostly based on "hard style" which means physical training, repetition, power and endurance.
- Wing Chun - Excellent kung fu MA and probably the easiest to get into (Wushu being the oposite and acrobatic). Great ROI on time invested and no need for hard training.
- Jiu Jitsu - excellent complementary MA for kung fu styles (like wing chun or wushu) since they are considered "weak" on the floor.
- Shorinji Kempo - probably the most balanced MA out of them all I've seen (I'll explain later)
- Kenjutsu - if you'd like to train with the sword :)
What you have to realize though is that you're not in it to be a ninja or whatever, you'll not fight anyone on the streets flying all over and shooting power orbs (right?), so you have to ask yourself what you'd like to train for.
As a fellow that sits around computers for long times I recommend one of these:
a) - Qigong - this is the base for everything, you will feel health benefits from it and geenrally feel more power flowing through you. If you can pick only one do this. Wing Chun is 99% accompanied with Qigong (also sometimes called Chi gung, kung) practice.
you can accompany Qigong with either Wing Chun (and Jiu Jitsu) if you want to train to be a competent defensive fighter or you can substitute Wing Chun with Tai Chi (Chuan) which is basically a battle version of Qigong so you can train only Tai Chi.
or b)
- train Shorinji Kempo and accompany it with Qigong
I also hear rather good things about Aikido and Hapkido, but I have no exposure to them.