I have a tough time getting a feel for tiers because I still switch off from regular to special too much, but I don't buy some of the middle tier choices. Basara's only solid move is dp+C, and everything else gets him killed. I can see misdirection helping him in high level play, but I always feel like I'm coming from behind with him. Rera is also overrated... she hasn't had a good way to break people's guard since she lost Nako's unblockable wolf jumping C in SSIV. Both Basara and Rera seem to far too often need to use their DM to bail themselves out - not the mark of a solid mid-tier character.
Some characters I think could make mid-tier in at least one of the games:
Enja, who can damn near kill you by comboing off of a standing B
Rasestumaru, who at least in special can break far standing B, dp+C, super
Tam Tam, because he's still Tam Tam
Zankuro, because of the green counter and green fist
Suija, agree with LWK that he's at least mid-tier in special if not higher
Some characters who merit more investigation:
Ukyo, and (at least in special) his AB swallow slice
Kazuki, and his combos off of qcf+B
Amakusa, and his high-low game off of the qcb moves
Jubei, who seems solid in both games