Geordi, his visor can pick up on all sorts of things. He's operated on Data so often, and has often shown the capacity to apply theories across disciplines.
Scanning bone breaks and seeing them as engineering puzzles, repairing ruptures, understanding stresses, seeing heart beats and heat signatures....
...100% Geordi hands down. Plus he's good with people.
Of course in terms of real life, James Doohan (Scotty), as he's a WW2 veteran.