Sorry, can't limit it to 5. Either due to usefulness of their data or curiosity about their content:
Aaron Johnson (rest his internet soul)
So many others, though...SaintGrizzly (rest his soul), BobSmith, Dean, RPC, Surgent...
UNFAIR question, I call BS! There are too many great contributors on this site to limit it to 5! Nanuls! Marcsoltan, Gangolf's Teutonic fineness...
Pah, unfair question. Next...