I really like the overall esthetic of #37 & #38. The colors are nice. The font is simple and easily readable. However, I'm not sure how a clover fits in with convenient, affordable dentistry. Can you come up with some different imagery?
#36 looks too much like the Microsoft Windows logo.
A subtle initials of "DE" for Dental Express. Trying to symbolizing the convenient & affordable, its shaped in a simple abstraction that also showing a subtle tooth drawing. Hopefully pleasing...