They all look nice but don't forget that you should be looking at both a color and B&W version of the exact same logo before choosing. Most game books have a B&W interior and your logo will be on the title/credits page in B&W, and on the cover in color, possibly. That means they will be one page flip away from comparison.
Personally, after oscillating for a while, I decided to go with a strictly B&W, simple logo for CMG. Looks good on the interior page, and it looks, not only the same on the cover, but also stands out when surrounded by mostly color.
I can't think of any companies that use alternate logos for color or B&W situations, but I suppose you could do that, too.