First, establishing ranks (JUST MY PERSPECTIVE, NOT CANON):
E Rank: Academy Student
D Rank: Genin
C Rank: Chunin (Haku, Kotetsu, etc)
B Rank: Special Jounin (Ebisu, etc)
A Rank: Jounin (Gai, Kurenai, Zabuza, etc)
S Rank: High Jounin (only known case is Shikaku. I'd place the Sannin, Akatsuki, etc at this rank as well as most Kage like Gaara, Tsunade, etc.)
SS Rank: High Kage? (Minato, Hiruzen, Hashirama, Madara, Itachi, Pein, Naruto, Sasuke, Third Raikage, Muu, Ohnoki, etc.)
Shikamaru: High Jounin / Kojounin / S Rank like his father. He hasn't shown much to imply he's much better than his dad.
Rock Lee: Jounin / A Rank like Gai. 8 gates kills you. That is not consistency, and does not count for much in overall ability. Case in point: Naruto would've destroyed the whole village post Konoha Crush if he gave in to the 9 tails completely, but he would've lose himself with that.
Sakura: High Jounin / Kojounin / S Rank like Tsunade. After her exploits in the war, she only became Jounin before the events of the war. Although a Kage, Tsunade was shown to be the weakest of Leaf's Hokages. So yeah, surpassing her only amounts to so much.
Hinata: Jounin / A Rank. Natural progress. She would've needed to reach at least this level to become clan leader.
Neji: Jounin / A Rank: Neji died young, without reaching his full potential. Had he lived, he probably would've reached High Jounin level at least.
Of course, all of these are my perspective as of Chapter 700.