Kingwood, Texas anyone?
Kingwood schools are excellent. My daughter was valedictorian of her class and was in a lot of competitions in the North Houston area. Kingwood was represented quite frequently in the academic world. She also took her SAT's at Kingwood High School. The only thing I can say about Porter is that I know they are building a brand new high school that is soon to open up. I passed it when I was traveling on 1314 between 59 and Conroe. I do not know much about the Woodlands except that there is horrific traffic and if you have to drive in to downtown from 45 during peak traffic time its even worse. Out of your 3 choices, I vote for Kingwood.
The Kingwood schools are actually in the Humble Independent School District (HISD) and they are great schools. I do believe that a good majority of the elementary schools in the Humble school district have no bus service which means they are all practically either within walking/biking distance or a short drive to and from the schools. I liked the idea that there were no buses that serviced my son's elementary school. Of course, that meant he either had to walk to school or I had to drive him to school and pick him up every day, he was a car rider. The only buses that picked up at the school were the daycare buses.