Have used an old version Paint Shop Pro (JASC) for many years, but I've wanted to find a new program that is actively being developed. Stumbled on Paint.Net a few years ago, but I've been unable to ween myself off of Paint Ship Pro because, despite being many years older, it is still better at a few things. Two things that I would like to see improved in Paint.Net before I think I could completely move from PSP:
1) One of the main things I use these tools for is to crop photos. If I want to change, by a bit, the area I've selected in PSP, I can simply put my mouse cursor on the edge of the selection area (using the crop tool) and drag to change the size of the selected area. MUCH easier than changing the selected area in Paint.Net.
2) The Text options in PSP are far superior than in Paint.Net. Again, I'm talking about a REALLY old version of PSP. It uses the concept of a text box when adding text. So, for example, I can drag the corners of a text box to change the size and aspect ratio of the text within the box, I can change the kerning of text within the box by simply dragging a slider, I can easily add drop shadow effects, I can use the mouse to select certain words or letters within the box and change the size, font, etc. Of course, once the text box is merged with the rest of the image it can't be modified in those ways, but it seems like Paint.Net's text controls would benefit by implementing a similar idea to PSP's text box.