Lens choice: Canon 18-135mm vs 28-135mm

[tmL]

Hi guys, so I am just thinking ahead about possibly replacing my kit lens before I go traveling in the fall and I wanted to hear your opinions on the Canon EF-S 18-135mm f/3.5-5.6 IS UD and the Canon EF 28-135mm f/3.5-5.6 IS USM. I've been looking at reviews and I'm leaning towards the 28-135mm lens but wanted to see what you guys thought.

I will be replacing the 18-55mm lens I currently have so if I do go with the 28-135 then I would have no real wide angle lens. I really want to know how the build and image quality compare between these two lenses though, since I would be willing to give up that flexibility for a better lens. They are around the same price so I'm having a difficult time deciding. Oh, and what is UD glass?

Thanks!

 

[chaosrealm93]

well... the 28-135 has two things up against the 18-135... first of all, it has USM. it would be quieter and faster and second, the 28-135 is an EF lens, and you could still use it if you plan to upgrade bodies in the future