Some comparable bicycles have a crossbar (top tube) that's horizontal:

![Windsor](https://i.stack.imgur.com/F6Oxi.jpg)

Others have one that's sloped:

![Trek Crossrip](https://i.stack.imgur.com/FNTZW.jpg)

What are the reasons for either frame design? Is it merely style preferences? Or is there more to it, like performance and comfort?

(Assume a men's frame.)