Having been tempted to look at a lot of products, I think I will probably end up doing a review.

Haven't completely worked out the methodology yet, but will involve using each prog to do a range of maps of types that I find useful as a DM (ie won't include maps designed primarily beauty or for use in books, games etc; they are surely always best done in PS/GIMP etc anyway). Ease of use and time taken to do each map will be important factors (as they are to me in real life), and the maps will be there at the end to be compared. Not sure of the range of maps yet - island/continent, local area (eg village/woodland), battlemap building (+ area outside or wood), battlemap dungeon, VTT, old-style TSR/DungeonCrafter scale. Will probably use the same images in each, but haven't finally decided that since some progs come with their own and maybe shouldn't be deprived of any advantage that gives them.

Haven't decided all the progs to do yet.
DungeonForge and MapX (of course).
Dundjinni, Fractal Mapper 8, Campaign Cartographer 3 (again of course).
Don't know whether I should include Dungeon Designer 3 and City Designer 3; they do exist but adding them really puts up the price of the Profantasy progs to being much more expensive than the others.
ViewingDale (though I'm not sure it is best described as a mapping program).
MapTool (would that mean I needed to do BRPG and other VTTs too?)
I won't include DungeonCrafter (1 too limited, 2 unfinished and fairly limited by current standards, 3 barely started). Haven't decided about AutoREALM.
I won't include PS (seems like overkill, and massively expensive) but will include PSE; will also include the GIMP and Paint.net.
And maybe others will turn up as I go along.

I'll post a link here once I actually produce something, but it won't be soon. Will take me a while to decide on methodology, design the basic maps, decide on the images/textures. That will probably be 2 or 3 months. And it will take time to make sure I'm properly familiar with each prog, so will probably produce them at approximately monthly intervals.

I like messing about with software, so I'll find it an interesting project to do.