September release and as usual the pictures are striking and amazing.
Rather than try to pick my favorite out of this latest set, I'm capturing a screen shot of one of the six pages of thumbnails. Give yourself a treat and browse through the album. According the numbering system, it looks like there are now 42,000 images of Mars now available.
Something else to check out is the Special Releases page - http://www.uahirise.org/releases/ - with HiRISE photos of the various Mars landers and rovers, views of Mars' two moons, as well as the Earth and our own Moon, as seen from Mars orbit.