hub is one issue
chain vs. shaft drive another
lubrication a third
re shaft drive I guess no one argues shaft drive is inferior for race performance. I presume shaft drive is inferior for race and likely distance touring or it might show up on a professional race bike. Weight and energy transfer are important. Shaft drive seems superior in terms of exposure to grease and just something different (cool) even compared to a bike with a chain guard. Being enclosed and few moving parts may mean maintenance frequency may be another advantage. I don't know how long parts last under the same work conditions so it may be wear or cost of maintenance is higher, lower, same?
Hubs: similar to shaft drive I guess weight and maybe gearing choices are not as good; again, maintenance, cleanliness and maybe wear or long term operating costs (including adjustment) are advantages.
Lubrication: Lubrication is good, dry is bad. Sticky lube holding grit on bearing surfaces is bad. Exterior, non bearing surfaces is nuisance. My take away is it never hurts to oil the chain, it's just messy.