For compression? 99% of the time I'm only extracting files, and I like the WinRAR interface better (although I usually use the context menu).
Yes, 7zip is superior fr compression. As far as extraction goes one or the other may extract a bit faster but I've never read anything to indicate which one and I doubt it is very noticeable if it exists. As far as the GUI goes it's really personal preference, you do know that 7-zip has a context menu as well though?
