Yeah Cobbs was a beast I took him due to his other ratings and he quickly jumped up to a 90+ overall after some development (I run a 4-3 3-4 hybrid). Radcliffe went to the Colts and quickly became one of the best LBs in the league. He went to FA after 3 years. At a 95 overall I made a huge bid on him but he ended up going with the Redskins.
Anyways to answer the OPs question. My most impact attributes (other than the obvious strength, speed, acceleration) is Awr, Prc first and foremost especially since I do not my LBs. The It would be Man coverage (I blitz and run man cover 2 and other man coverages alot). Block Shed is next (gotta be able to stop that run). Pursuit, Tackle, and Zone I like to level equally after that.