I honestly would have to choose either Neji or Shikamaru. Both have very a very diverse character, and have grown significantly over the series. As for why Neji, his bloodline lime is awesome, not too powerful and still has a weakness, making him realize it in order to grow and he also knows the Taijitsu (SP) which can be used as a stand alone, or in combination with his Byakugan to inhibit an enemy's ability to use chakra. His bloodline limit allows for a quite impressive defense, and a very powerful ofense when used in conjunction with his other abilities.
The only reason I'd choose him over Shikamaru, is because shikamaru's abilities allow him limited or no movement while active, leaving him open to attack if his plan goes sour at any time. The major plus side is that he is a tactical genious so to speak, when given time he can have a plan to account for anthing that may occur (given the knoledge he has pertaining to the mission and his group) and can reason out a situation as it unfolds.
As for you who chose Gaara, or Sasuke... >_< Why? Sasuke is Emo, and Garra is a crybaby... "Waa, I got hit" "Grr, I'm an angry monster now, blaaah" Granted, when Gaara came back to assist in the fight agains the sound ninja (I think that's when it was) he did look much cooler, and seemed to have a much less childish air to him. So, in the Gaara goer's defense, he has inproved as a character. ^_^. Improvement and becoming dstronger beyond physically is one of the most redeeming qualities in a character. <~~~(cool guy stance)