Michael - I tend to like zoom lenses because of my street and event photography. For instance, my main lens has been the Sigma 28-200mm. That way I can go from wider angle shots to closeup portrait without having to worry about changing lenses or carrying extra stuff. For what you want to do, those two lenses will be good. I'd probably opt to use the 100mm and step back a bit rather than the 50mm for portraits. Although, I have seen some photographers who have shot portraits with 85mm and even 50mm and they have looked great with no distortion (I have no idea how they do that, I've never been able to do it). With what you said above, the three choices you have made look to fit what you want to do and how you want to use them. I would still prefer the Canon 28-135mm IS over the Sigma, but you have to go within your budget. I know that feeling well, I had to figure a new flash and off-camera shoe cable into my camera budget since I can't use my current TTL flash setup with the 10D. :/ Oh yes, one thing you want to find out before you buy it is if the Sigma lens works correctly with the 10D. There are some Sigma lenses that do not. You can send them back to Sigma for reprogramming, but that's just a pain in the butt. -=>Donald