Make a list of everything you would like to have at the touch of a finger.
Talk with a number of installers to see the possibilities of your system.
Make sure you include remote internet access if you travel or are away from home often.
Consider the users, and make sure the system will be usable by everyone in your home.
Unfortunately, although both companies make great statements as to home automation systems, none claim to be able to quiet a screaming two year old or motivate a recalcitrant teen. Oh well, maybe next year.