Well...i would have to say that it depends on a lot of different situations.
--for instance you would use a different size hook for -
--Live Lining Bait
There are many varied hooks out there and some will appeal to certain anglers for different reasons. I would reccomend reading up on some of the frums to see what other people have to say but basically your just going to have to try everything and see what you like the most.
For just about everthing I do I use 5/0 or 6/0 for big chunk. Any bigger and they may spit it sensing the hook and smaller you might not expose the point which I always do. Tied to a fluro leader as long as the fish your going to catch (don't get to carried away here ;-) and barrel swivel tied to your main line unless your 3 waying it or whatever else there is. Fishing hot so get the hell out there. Wish I didn't live 2 hours awawy or I'd be drifting some eels right now.