It seems like the more zipper you have the harder it is to keep water out of your panniers. While neither panniers you mentioned are "waterproof", I suspect the top loader will be drier. FWIW-- One of the main reasons I switched to Ortlieb's was the fact that they keep things dry. I also try to organize both front and rear panniers so that I don't have to do much "searching". I'll take the small inconvenience of having to dig for things once in awhile to the hassle of using garbage bags (which you have to dig through anyway) or soggy contents. I also have not had real good luck with raincovers keeping things dry in pre-Ortlieb days.