Depends on the character for me, but I prefer detailed-especially when making fursuits. It always figures that someone tosses a ref to me, I follow it to a T, and that spot or stripe or whatever is incorrect.
It really depends on what the character is being used for. If it's just to have something fun to draw, then by all means, just do a simple reference. If, however, you want to put a lot of backstory into the character for one reason or another (say you're using said character in a story of some sort and you mainly want the reference for yourself, but other people can make use of it), then I would say to go with one that's more detailed. It helps to flesh out the character and you get a better feel for them. It would also help you maintain a level of consistency.
...I suppose deciding which of the two is better is also dependent on personal preference.
I love detailed ones I don't have any of my own currently, but I love detailed ones with info on everything about the character Mostly because I don't want to mess something up if someone asks me to draw something, or I don't want them to mess up on my chars either,lol, but then I also like learning about the char and their design Idk, I guess it's just me lol
I feel like one full-body and then some pics of any details that aren't on the front of the char is better than a cluttered mess. At least better for viewing. If I were ever to make a reference sheet for myself, I'd want the cluttered mess, but as far as looking at other peoples', simple has a higher chance of me liking it. Though I suppose reference sheets aren't meant for liking, they're meant for... referencing...