Which one is a better lens?

I'm buying a dslr camera. So I just want to know the optical zooming rate of Nikon 55-300mm and Tamron 70-300 lenses. And what about 18-35?

"Optical zoom" is a P&S camera term. It doesn't really apply to DSLR lenses.

All you do is divide the larger lens number by the smaller.

For example…

55-300mm= 300/55… 5.5x
70-300mm= 300/70… 4.3x
18-35mm= 35/18… 1.9x
50mm= 50/50… 1x… No zoom

But the "zoom rate" doesn't tell you anything. It is only for P&S camera users to brag to their friends about… "Ohh, my new camera has a 45x zoom and yours doesn't."

A 100-300mm 2x zoom lens doesn't do you any good for taking landscape or large group photos, nor does an 18-35mm lens do you any good for getting a close up of a bird in a tree.