You may want to take a look around FUM.com. They specialize in the VTT aspects, but have a bunch of stuff in that realm including comparison tables and whatnot. I think they have a comprehensive list of all the VTTs that are out there as well.
Raster (bought) [e.g. Photoshop, PaintShopPro, Painter]
Raster (free) [e.g. GIMP]
Vector (bought) [e.g. Illustrator, Corel Draw, Xara]
Vector (free) [e.g. Inkscape]
Vector (Symbol driven) [e.g. CC, Dunjinni]
Online Generator [e.g. City Map Generator, Fractal World Generator]
Fractal Generator [e.g. Fractal Terrains]
3d modelling [e.g. Bryce, Vue Infinite, Blender]
Scanned hand drawn maps
Drawing Tablet and pen [e.g. Wacom]
You may want to take a look around FUM.com. They specialize in the VTT aspects, but have a bunch of stuff in that realm including comparison tables and whatnot. I think they have a comprehensive list of all the VTTs that are out there as well.