From my one relationship with another man that involved sex, I'd think I have a clear preference for bottoming. Obviously I know that could change with someone else. But I'm curious, how much more at risk is a bottom than a top from infection. Obviously I'd use protection, but just in that 1% time when there's a tear in a condom.
Studies seem to put it at about bottoms having 3 times greater chance of transmission from the top, compared to the top contracting it from the bottom. (bottom: 1.7%, top 0.62%) You can see a table displaying the results from various studies here on Wikipedia: HIV Transmission
