I've heard good things about Bayou City Crossfit in the Heights and Pinup Crossfit near downtown. I believe they have the same owners.
My BIL goes to Crossfit Elevate, but that's much to far west in Katy.
This. An H&Fer on here goes to PinUp and loves it. I have heard EXCELLENT things about Bayou City Crossfit. In the Crossfit Southeast regionals, they placed #1 and #2 I think for the guys and also placed in the girls as well.