Jake, some people (myself included) prefer the white glues, like Tandy's Leather Weld. Advantages: you don't have to coat both pieces of leather, no nasty smell, and it takes a while to dry so you can reposition if necessary. Overall, white glues are easier to use and more forgiving. However, if strength of the bond is the most important thing, I believe contact cement is the best option.
One more thing... Regardless of the glue used, stitching the two pieces of leather together will always add a lot more strength. Good luck! -Alex