Assume a mass casualty type situation. Something along the lines of AR-558 with physical wounds ranging from phaser and disruptor hits, to concussions, broken bones, and the like.
Each Chief would be from roughly halfway through the run of their series with whatever knowledge and experience they had at that point. Each would have access to whatever kind of portable medical kit a medical officer of their time would have brought for such a situation. There are no able bodied personnel to help. No they don’t have access to a transporter.
Geordi, his visor can pick up on all sorts of things. He’s operated on Data so often, and has often shown a 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.
Except for women he finds attractive.