Assume you mean the 18-70?
The 18-70 is a perfect walkabout lens, light, nice range and pretty good IQ, never used a 16-85 so cant comment. The 17-55 is heavy but feels good, especially on my D300. Decent wide open, it was sharp and crisp around f4. It is the better lens by far, but a
second hand one will be £550 minimum (closer to 600) and new will be around £950. The 18-70 can be had for £120
second hand or £199 new from Jessops.
As a general walkabout, taking pics on holidays, kids, etc... I would go with the 18-70. If I was doing any sort of paid work, or did a lot of low light stuff, then the 17-55. Of course, money comes into it. If you have a little stash to burn, no harm in the 17-55, if not, the 18-70 is the way to go, especially as you could use the difference for other lenses such as a prime or 70-300VR?