Sigma 18-50 f/2.8 Tamron 17-50 f/2.8 Tokina 16-50 f/2.8 Sigma and Tamron are both about $399 while the Tokina is about $200 more. Every time I think I have it figured out I read another review that sways me another direction. So... which would/did you choose and why? This will be my first of a 2 or 3 lens kit to satisfy my needs from ~18mm - ~200mm, poor man's Nikon Holy Trinity if you will. I decided to start with this range because it's closing on winter here and there wont' be much need for big zoom until Spring, at least for me. Most of my shooting this time of year is landscape (winters magic) and in house (kids). PS I have a Nikon D90, so lack of an internal focus motor isn't a deal breaker.