18-200 3.5-6.3 Tamron vs. Sigma

[Igor Roshchin]

Hi All:

Even though "super-zooms" usually have inferior design to more moderate
zooms, I started thinking about buying one of these for those situations
where I need to switch between different types of focal lengths and do
not have time (or too lazy) to swap lenses.

So, I am looking at 18-200 f/3.5-6.3 that are made by Tamron and Sigma.
Does anybody have any experience with either of them?

The one from Sigma is unavailable that suggests to me that it may be a
new lens that has not made it to the stores yet.

All you comments and suggestions are appreciated.

Igor