Something about the 18-55wr keeps calling me back - I've had two now. It's the overall package that's hard to ignore: really light weight, quick shift, weather seals (even if the k-x has none it's reassuring) and quite good image quality. Also takes smaller filters than lenses that try to replace it; when matched up to my 50-200wr with a 49/52mm step ring, one set of 52mm filters can do it all!
Something about the 16-45 keeps calling me back - I've had two now (boy that sounds familiar..). It's bright at f/4 through its range, fairly light weight, and its 16mm f/4 setting keeps me from spending all my cash on the 15 Limited :^) It also has quick shift, which I find quite handy. Color and contrast are very good, and the latest one was well treated and at an excellent price. Part of its issue before was that I was trying to go with 16-45 and 55-300, and that gap sounds small but seemed to be something I need. I've closed a part of that gap with the 50-200, and I will just crop as needed (or maybe that 18-200 Sigma will be attached to the camera that day?). I feel better about this lens now that I've tried so many alternatives, and for outdoor/mountain scenery I feel the wider range will be valuable. Again: we shall see..