For Windows, take at look at Xara Photo and Graphic Designer. It's principally a vector Illustration program but includes some photo manipulation capabilities too (cropping images, adjusting brightness and contrast etc).

The interface is far superior to Illustrator and it's extremely fast in performance.

I have used this program for many years and recommend you give it a try to see if you like it.

There is a free trial version of the software on the Xara website

http://www.xara.com/uk/photo-graphic-designer/