Here's a nifty page which shows GM and VE side-by-side, with slaved navigation. It's quite handy for seeing differences in map rendering and imagery.
For my area of interest (Victoria B.C.) my 20-second appraisal is that they both have aspects of their rendering which are better than the other; and VE's imagery coverage is more limited than GM's (probably due to this deal).
Evolutionary Database Design
23 hours ago