Well honestly, it's like apples and oranges.
To me that's like comparing TE's to WR's but if that is the question, no.
LT is clearly the best LB of all time
Best OLB... I agree. But MLB is a toss up IMO. LT redefined his position, but there are many great MLBs.
You got
Butkus
Singletary
Lewis
Nitschke
Willie Lanier
Lambert
Seau
OLBs:
LT
Derrick Brooks
Derrick Thomas
Bobby Bell
Ware
Haley
Overall LB, between Butkus and LT