How people define sharpness clearly varies from person to person.
35mm find that prime. - PentaxForums.com
We definitely need to see what the OP defines as a "sharp" image.
Many people are looking at how the image is rendered, micro-contrast, colour cast, contrast etc. and evaluate the whole image and call it sharpness. The only thing that's really important is how the lens renders. Snide commenters have looked at the spec sheets and commented (in reference to my 21 ltd.) "your lens isn't the sharpest." If I like how it renders an image, I don't care much about how technically sharp it is. That's why I can go out with my FA 35-80 and get great images that make me happy, when many, prejudiced by spec sheets wouldn't touch that lens. And my charts have shown, many of those who wouldn't touch a lens like that actually prefer it's images in blind testing if the image has been downsized. These kinds of biases can diminish your enjoyment of photography.
But bottom line, "which lens is the sharpest" depends on how you define sharpness, and even if you go for the technically sharpest, buying the technically sharpest lens does not translate into, 'if I buy the sharpest lens, I will like it's images best in a blind test." My examples show, you probably won't. The odds are against it. Lens design with regards to contrast, micro-contrast, rendering of OoF areas, colour rendering is way more complicated than straight up sharpness.
That is sad news for those who just want to purchase based on spec sheets. Each lens is a combination of important characteristics, many of which can not even be measured. For a person to really like a lens, those elements must be combined in a way that caters to their own individual taste, and no one of can guess what that might be for someone else.
And for many of us, our favourite lens is the one that is on the camera that day. Of my 20 lenses, none has never given me at least one image that suited it's characteristics. Even my soft hated old Vivtar M135 2.8 has given me a couple images I'm happy to share. The answer to "what is your favourite lens?" depends on what day it is and how I'm feeling that day.
My guess is, if you have to ask which lens is the sharpest? would be, "if you have to ask, maybe you just need more lenses to choose from." If you have enough, and you're familiar with them all, on given day, one of them is going to suit your mood.