It's definitely a matter of personal preference.
DAK is a beautiful park. I think it is the most beautiful park on property and I love to soak in the atmosphere. But it is severely lacking in things to do. Especially if you have kids. Also, if you have a decent zoo nearby, well, it's basically 1/2 zoo. We skip DAK 2 out of 3 trips. It's something everyone should do once. But I'm perfectly content to wait until Avatar and the night time show open before revisiting that park. If you think you will go back in a few years, I would wait until they finish the additions before going.
DHS is a Disney's de facto thrill park with two of the biggest thrill rides on property. Having said that, it doesn't provide the same thrill level of your average coaster park. There's lots of shows which are fun once. Repeatability is very low. Like DAK, it's lacking in rides. But since it has been around longer, it has received a few more additions. It's easier to make a full day out of DHS. It's open longer and has a nighttime show.
For us, we go to DHS one day out of every trip and generally skip DAK. Both parks have their strengths and weaknesses. You should pick the one that suits your preferences. A first time visiter to either park will have a fun and full day. The half day park really only comes into play on repeat visits.