Designers usually add those colored gradient backgrounds to make the logo pop up so it looks attractive. It's kinda an illusion. Unless your site theme uses the same background, I'd suggest you to try placing them on a white background or whatever theme your site have so you get the "real" picture of what kind of impression it makes to your visitors.
The fonts you use on the logos should define the message it's trying to convey to the visitors. For ex, the font on the 2nd logo makes the "$" symbol look more credible than the other two. The same goes for the colors as well. You gotta highlight the "Month" as well like some covered rectangular box behind the words "Month Online".
Most importantly, None of the above suggestions apply if you're gonna sell a WSO on WF.