You have a point here. One of the reasons Gaara lost to Deidara was that Gaara was above Sunagakure and that Gaara was cocky, and the only reason Sasuke won was that Sasuke luckily had lightning release. If Sasuke and Gaara actually fight, I am not sure. I personally like Gaara a lot as a character, and I hate worthless Sasuke. In fact, Sasuke is my least favorite character from Naruto aside from a few other characters like Tenten. Where they fight matters as well. If they fight in a desert where Gaara doesn't have to take time to create sand by crushing minerals underground, then Gaara has a good shot at winning. However, if they fight in a meadow, then it'll take Gaara a little time to create sand by crushing minerals underground with his existing sand, so Sasuke has a better chance of winning in this case, I suppose. Also, Gaara can block almost all attacks that Sasuke has. Gaara even guarded against Amaterasu! One problem with Gaara is that his sand can't crush Sasuke's complete Susanoo, so it'll take a long while before Gaara can actually harm him (I believe Sasuke can't use Susanoo for an extended period of time). I guess Gaara can fly around on his sand and because Sasuke doesn't have wings anymore, it can be hard for Sasuke to get him, so I'd say Gaara certainly has a good chance of winning against Sasuke.