You have Aperture. Aperture comes with a very broad, robust set of image development tools. You can not composite within Aperture (you'll need a graphics program to add data, text, or graphics primitives to your images), but you do most everything else.
(You can add text with the excellent _free_ plug-in, Border FX.)
What is it you are trying to do? I cannot imagine a level of image development beyond which Aperture can take you (but if you want to do graphics editing, you'll need a graphics program).
Regarding "on-board" filters Aperture refines to the classical filters for turning 4c images into black and white, sepia and a few more like cross development, cyanotype and toy camera.
For special photo filters you might have a look at e.g. http://www.apertureexpert.com/presets/