Wow, tough call.
For his extraordinary ability to explain things in clear concise detail for the relative newcomers to the XS650 machinery - XSLeo.
For his limitless library of finely detailed pics of XS650 mechanisms, and sourcing knowledge of esoteric tooling - 5Twins.
For his knowledge and abilities in the wrenching arena, postage support of needy members, and general cleanup of objectionable threads - gggGary.
For his ability and patience in explaining electricals - RetiredGentleman
For his VIN and historical support - 650Skull
For his well detailed and historical threads on XS650 systems - INXS
For his research, reporting and insight into the foibles of the XS650 - XSJohn (RIP)
(I wish I had known him)
Many honorable mentions for those members who put together YouTube how-to's...