I have been to all 3 trax that you mentioned. I think the long track at Clutch City MX (in Humble) is my favorite. I went there about 1 month ago and this particular long track was very rough, but lots of fun all the same. Next, I like San Jacinto MX Park (the Splendora track)...but my big heavy 4x4 quad is not really meant for getting great big air like the rest of the sport quads are, so this track is not my very favorite. Lastly, I ride at 3 Palms (in Conroe) b/c its convenient/located near my home. 3 Palms would be a lot more fun if they let quads ride on the main track...unfortunately, they only allow quads on the River Track on most days and they only open the Main track up to quads on a few Monday nights each month.
If you like riding in the Texas area, you should check out www.texasatvs.com
That site has good bunch of ATVers on there who discuss local tracks like the above all the time. Check it out sometime. I still like this forum the best for finding technical information about my quad.