If it's for your Hoyt, then I'd say some 1.75" quickspins, they stabalise the arrow fast and are very light. If it's for you traditional bows, then feathers would work better as they are very forgiving to contact with the bow and will straighten your arrows out fast as well as soak up some of the arrow vibration/flex. I would imaging 4" would be more than enough though, not sure you'd see much more benefit from 5", guess you'd have to experiment there
I used 5" feathers once on my indoor arrows, but I cut the profile down with a template and scissors, so they had about the same surface area as 4" feathers, so there was less chance of contact with the rest.