Gentlemen, Gentlemen. There's no need for dispute. This matter can easily be resolved by referring to:
8TB's Super Unbiased Rankings of Daval3D's Most Attractive Female Characters
This has been peer-reviewed, subject to stringent control experiments, and substantiated by primary sources. So I have written it, so shall it be known.
In all seriousness, I think any of the featured older female characters in Daval's three major comics can be atop anyone's list. I agree with Mekalam in that I'd probably give the nod to Amanda over Alexa, but we're honestly talking about razor-thin margins here. Alexa, Amanda, Lana, and Sarah, are among the sexiest characters I've seen, and giving a nod to one over the other is like choosing between Mac & Cheddar Cheese, Mac & Pepperjack, Mac & Smoked Gouda, or Mac & Gorgonzola. Regardless of your preference, you're in for a good time.