So bottom line is that you don't have to spend a load of money on your equipment to get good photos. Often to improve your photos you simply need to change technique. A lot of people have not mastered the equipment they currently have, and they are under the idea that they just did not spend enough. What you need to ask though is what are you currently dissatisfied with? What are you not currently able to do? Then find out if maybe it is technique that you are struggling with. Or, if you do need something else to help you get where you need to take your photography make sure to define well what you want to do. There is no "perfect lens". Keep in mind too that one of the reasons the lenses can be swapped out on a DSLR is that no one lens will do it all. The superzoom lenses (like an 18-200mm) are built with a load of compromises to get the lens to work at so many focal lengths. So it is really good at a lot of things (or some of them are not even really good if they are the really cheap ones) but they are not great at any of it. I like using the Sigma 18-200mm if I want to just grab the camera with a single lens for a walk about all day with the wife and don't want to schlep my computer bag everywhere (and get dirty looks for constantly stopping and changing things). But I would not use that lens for shooting models or doing portraits of people. I would definitely not use it for night time sports photography. You could shoot your kid playing soccer on a sunny Saturday when you are shooting f/8 and it would do pretty well though. But if you are wanting to shoot sports for getting published in a magazine you will need the better resolution of something like the Tamron, Nikon, or Canon 70-200mm f/2.8 lens, even if you are shooting it at f/8 aperture. It is all about the right equipment for the right job, and sometimes that can be the lowly kit lens to shoot macro photos of mushrooms at your local nature center.