Quote Originally Posted by bittu
I am not able to make decision between EF-S 18-200 or EF 28-135.

That's easy. 18-200 hands down. It not only has far greater range, but it is optimized optically for your sensor size, so it has higher contrast and resolution than the 28-135. (The 28-135 must cover a much larger image circle, so it's no surprise that it is beaten by the 18-200.)