If you're using a rope 100% for aid then a larger diameter would make sense. If you do a lot of multi-pitch with a little aiding then a Ø9.8mm would be fine. The larger diameters are heavier but add the extra security. I have used my 9.8mm new england rope for almost all my climbing in the last 4 years from sport, trad, and aid / big wall. It's all about hom much you want to pay too. I prefer dry ropes with either bi-pattern or bi-color. I don't want to be looking for a middle mark in the dark when trying to get off a route and the extra cash for a bi-pattern is worth it for me.