Since this thread seems to be about all things related, lets talk director. I gave the matter some thought and my personal choice would be Matt Reeves of Cloverfield fame.
First of all, Cloverfield, come on, easily one of the best films of the year. Specifically I liked how he was able to show the monster destroying the city in the background, but the focus of the film was very much the people on ground level, the human story really came though. Plus even with everything going on he was able to inject a little humor (I found the conversation about the 'flaming homeless guys' hilarious). Also having a background in TV drama and not just big budget sci-fi means he's not just about the monsters and can show people's lives and show character development
I would be happier with an Animorphs film in the hands of a 'grown up' director, rather than someone who's whole background is kids films, I can trust him not to sanitise the darker aspects of the plot.