The Cowboys are number 1 for sure, probably forever.
The next three are completely interchangeable. If the Mavs would win just ONE championship they stay at 2. They have been around long enough for that. The stars only had a few good seasons, and hockey is not a very popular sport in Texas. That being said, the Stars have to stay above the Rangers since no one believes in that team. I love them, and will always watch, but man, I can see why people won't follow them.