Photoshop, a worldwide-known program by Adobe, is also an excellent choice. Photoshop has an immense number of filters, and a decent amount of effects.
Depending on what your price range is, certain programs might appeal to you. Paint Shop Pro is only $99.99, while Photoshop can go as high as $500.
Either program mentioned here is an excellent choice for images. Whichever you choose will probably affect the quality of your images.