Mike Curtis is in the same class of middle linebacker as Sam Huff and Dick Butkus, the dude was a fuckin animal.
I didn't say Lambert or Buonoconti because they played in a 4-3 and 3-4 defense and while certainly a hall of famers and all time greats, as far as I know none of the other 3 played in 3-4 alignments.
Buonoconti was more of a technician, always reading the play, being in the right spot, making the tackle with surgical precision. He was not a physically intimidating type who would manhandle you or annihilate tacklers. He just always made the play. Jack Lambert, on the other hand, was a scary fearsome intimidating SOB who would hit you with slobbernockering force. Both are worthy HOF linebackers, but very different in their style.
And Mike Curtis was like a rabid animal on the field and a hell of a lot of fun to watch.