That's because one is a tele another is a wide. It's just at that moment you need a wide more than a tele, so you feel that the wide is very good to use. Imagine you need to shoot a bird, which will be your 'best' lens that time?

Well, since im using DX, 70-200 seems to long, 17-55 just nice.

Also, D5100 so small the body, with 70-200 attached, its hard to handle.

Ahh... then I think the definition of 'best' lens is vague here. It should be better suit your needs or easier to use.
In general, the better should be talking about overall (e.g. built quality, image quality, performance, etc).

so is the 17-55 worth the money?
btw, i also find its slightly unbalance even on a D7000, thats why got battery grip.

midnite spam pic xD

Best? Better than the 70-200?

Btw, the 17-55mm f/2.8 is bigger than 24-70mm f/2.8

In that case, the 70200 would be the obvious winner

The 24-70mm f/2.8 is bigger than the 17-55mm f/2.8.

83 x 133 mm vs 85.5 x 110.5mm
900 grams vs 755 grams

That's why I was surprised when I first read which was the 'best' lens 
I was also surprised, was at Nikon BTS that day with Calvin, he mounted the 24-70 on the D5100, while I have 17-55 on the D7K, somehow, the 24-70mm looks thinner and smaller.

http://nikon.com/news/2011/0921_digital_01.htm

Nikon Mirrorless Camera announced!

2.7 crop factor based on the below engadget first hand info.
http://www.engadget.com/2011/09/21/nikon-u...p-cmos-2-7-inc/

Was wondering what will be the sensor size of this guy.

Previous rumoured around the same size as high end compacts, e.g. Panasonic LX5.

Anyway, DPReview mentioned the reason behind such small sensor... is not to disrupt DSLR sales/market?

If such a small camera can be as good as a DSLR, then DSLR already need to be so high performance like medium format camera, e.g. Hasselblad ...

The V1 and J1 share nearly identical specs, with the latter model sporting some fairly minor tweaks. Both ILCs include 10.1 megapixel CMOS sensors, HDMI / USB connectivity, a 1200fps slo-mo capture mode (!), 3-inch LCDs, 10fps shooting, high-res electronic viewfinders, and full HD (1080/30p) video capture -- though 720/60p and 1080/60i modes are thrown in for good measure. The J1 touts a built-in flash, 73-point AF system, dual-core EXPEED processing engine, and a ritzy phone detect system, while the V1 boasts an EVF and supports an external flash, as well as a mechanical shutter, stereo microphone input, a "multi-accessory port" and a magnesium alloy chassis.