One of my favorite filters for photography always has been the Nik Collection, which was bought by Google a few years ago. Since this time, the professional filters were available for a very fair price around 130 $ / 100 €. Before this acquisition the software was only available for professional photographers, starting at over 600 $.
Today Google made the filters available for free, so this is the perfect reason why you should try them now, because they are a very valuable additional set of tools you can use to improve your photos. The title image of this blog post is already showing the difference between a shot I took in Iceland last year at Landmannalaugar. The filters may not obviate the need for professional software like Adobe Photoshop, but they are a great way to get the very last out of your photos and to improve the speed of your workflow at the same time.
You can download the complete Nik Collection here.