if you don't mind standing out, the yellow with black lettering has nice contrast, looks bright and sharp.
with your black parts, you're not overdoing it. just don't get anymore yellow parts on the bike. keep just the frame yellow, get black for everything else, and your bike will definitly be a looker.
if you're not a yellow type of guy and would feel awkward riding one, then i would go for the silver with red.
the plain silver is nice too, but it's true, there are a lot of silvers out there. i'd rather have a gunmetal gray color over a plain silver.