My team would be:

Gai - He's way cooler than Kakashi, plus he adds an important part to the team, namely...

Rock Lee - Best hand-to-hand combat fighter
Hinata - Better than Neji on a team; has the same abilites except for tajuitsu , and Rock Lee is a better fighter than him, so he's excluded (and he's no teamplayer). Plus she is a healer, and that my friends is a super ability in a team.
Shikamaru - The brain, and when he's on a team he's not lacy or unmotivated, that's teamwork; and can disable all oponents with his ninjuitsu.

Other than that, I have to say the best *existing* team is the one with Hinata.