Is there an image editor like Windows' Paint for OS X? I tried out several image editors mentioned on this site but some of them (like Pixen and Seashore) were very disappointing. These apps were too simple and low level.

What do you suggest for a (preferably free) image editor on OS X?

P.S: I was using GIMP on Linux and also know that it was released for OS X too, but I want to find new good applications.
You could try Paintbrush (free).
As quoted from its website :

Paintbrush is a simple paint program for Mac OS X, reminiscent of Microsoft Paint and Apple’s own now-defunct MacPaint. It provides users with a means to make simple images quickly, something which has been noticeably absent from the Mac for years.