Many needs at the moment.
I would start with O-line. Give Eli time and he is a top notch QB. It would also help the running game. If AB can get healthy I think Brown and Wilso n could be a good trio. AB is a tough guy, I hope he can get healthy.
Martellus Bennett can not be your primary TE, be has hands of stone. I would keep Bennett if the price is right as he is a good blocker. Hopefully th ere is a decent veteran TE with good hands in free agency.
I think WR is OK although we all know Nicks will be hurt again next year. Hixon has been solid but again an injury waiting to happen. WR is not a pr iority.
D-Line - Osi has to go, he is nothing more than a 3rd down specialist at this stage of his career, and not a very good one. I would have a sit down wit h Tuck and see if he wants to still play football. Doesn't look like that is the case. Hopefully Rodgers can come back healthy next year and help stre ngthen the run defense. Canty needs to take a cut in pay. If there is a good d-linemen in the 2nd round I would take him. Also look for a decent FA. Kiwi should a full time D-lineman.
LB's, yuck. Can only plug so many holes in one year. May have to put up with this very weak group again. Boley looks so slow that I would conside r to let him go. Rivers will be injured so can't consider him. Go with the young guys and see if they can improve, quickly.
If TT can come back healthy (highly unlikely) they would be OK. Webster has shown that he is a 2-3 CB at best. Kenny Phillips will most likely be i njured so keep Rolle. Hopefully Hill will develop into a solid DB. Prince played well but again another very injury prone Giant.
I am not a big Perry Fewell fan but continuity is important. If a really top notch DC was available I would consider the change.