Personally I use Photoshop.. why? cause that's what I started using back when I studied journalism.. as for something I could not live without it would either be the layers or the selective color adjustments.. Photoshop might be a bit massive for somebody that isn't used to it.. but I belive you'd get a basic grasp of it before too long.. I'd stay away from most ad on plug-ins though.. they tend to give a very "plug-in look".. there are some exceptions though.. as to what I do in postwork it varies very much from image to image.. but I always do clean up of joints, hair and color adjustments as a minimum..