All of the schools in N. Tarrant County are great! The best athletics are in Southlake/Carroll, Grapevine/Colleyville, Keller, and Northwest ISD. They are also academically fantastic, only varying by degrees. Decatur is also great. It is a slower pace with the students being of more varied backgrounds. I suggest that you visit all of the areas and then you can decide which suits you and your family the best.
Visiting an area is always the best if you are close enough to do that. Pictures aren't always worth a thousand words when checking a home out ONLY through the MLS sheet. Drive the neighborhood and see for yourself. If I can help you in any way, PLEASE email me with your criteria. I too sell all of Wise, Parker and Tarrant Counties.
Interesting question. It all depends on your definition of the best. Of course it may also depend on the price range you desire to purchase. As mentioned above many consider Southlake, Colleyville, and Keller to be great school districts. Northwest is probably much less in the spotlight, but in my opinion is also an excellent option. It might also depend if you want to live in the big city or a smaller community. If you need information about test scores, parent reviews, rankings, etc and know the specific school name, you can check it under the schools listing on my website.