Best Walk Around/ Travel Lens : Canon Vs Tamron

Hello!

I'm looking to buy a good walk around lens for an upcoming vacation trip. I'd like something that covers portrait, cityscape and landscapes with a budget of $500 and below. I've narrowed it down to the following:

Canon EF-S 17-85/ 4-5.6 IS USM
Canon EF 28-135mm f/3.5-5.6 IS USM
Tamron AF 17-50mm F/2.8 SP XR Di II VC
Tamron 28-75mm f2.8 Di

From what I've read so far, it looks like the differences lie in image quality and lens build quality - I'm looking for the lens that offers the best image quality (sharpness).

I'm shooting on a Rebel and already have a Canon 50 mm. I'd appreciate any feedback on the lenses I mention above or anything else I've missed!
Thanks!