From everything I have read/heard, this is what I got:
Lanier: came in out of shape but has busted his butt since he's been here, will probably start nickel
Moore: the real deal, nuff said
Harris: haven't heard much but I know he certainly looks the part, my guess would be he starts immediately on special teams and probably second string starting out.
Coleman: has continued to improve on his big spring, has come out of summer as one of the strongest DBs, surprisingly. if i was gonna guess i'd say he's Lanier's biggest competition to start at nickel right now.
Clear: is playing TE and has apparently looked good in 7 on 7s