Gaara:
Like Naruto, he's been through some **** in his life. He may have gone down the wrong path when he was younger, but he redeemed himself. Hell, he even beat Naruto to becoming a Kage. It was stated that the elders of the Sand Village agreed to make him Kazekage so that they could "keep an eye on him," but he's proven that he is indeed worthy of the title, as shown during his battle with Deidara and his appointment as the Regimental Commander during the war.
He's also quite strategically adaptable, as shown during his battle with the troll-kage, utilizing the basic principles of heat transfer and thermodynamics (relative thermal conductivity and phase transition phenomena) in order to achieve victory against an opponent whom Gaara was weak against (due to the oil). This makes Gaara a bit like Shikamaru, being intelligent enough to overcome tough opponents through tactics alone, even when his opponent has the upper hand.
Gaara has demonstrated a great deal of character growth, such that his development even rivals other members of the Konoha 11. As a secondary supporting character (with primary supporting characters being Kakashi, Jiraiya, Sai, Yamato, the other K11, etc.), Gaara has received a decent amount of attention from Kishimoto and I think it is well deserved.
Lastly, Gaara's fanbase typically doesn't overrate/overhype him in an annoying fashion (see Sakura fangirls and Minato/Itachi fanboys for the converse situation). We realize that there's several other characters that could out-perform him in battle. Regardless, we like his character for his personality and his story more than anything. He is pretty strong, but his fighting skills pale in comparison to his other attributes.