When using regular search to look for images, the "Aspect Ratios" section has buttons at the top of its drop down for "All Wide" and "All Portrait."
The user settings section for Browse has a section "View Filters" where the fields contain text fields for the pre-set Resolutions and Aspect Ratios we'd like to use as a default.
It'd be a nice addition to the user account Browse Section's settings if we had a similar set of menu/buttons when setting our accounts defaults/settings that we have available when setting the search parameters on the main part of the site.