I find 8/8"+ the most enjoyable to use because I don't have to rinse every stroke and it's just plain fun. But a 9/16ths with a rounded tip is the most maneuverable for me.
Well I have only tried 4/8ths to 7/8ths and so far I think my favorite is 6/8ths. I also like razors to have a bit of heft to them so I prefer my Le Grelot's and Filly's to my Dovo's.