Which aperture range is better?

The lowest numbers decide what the maximum aperture can be set. It doesn't mean that it can't be set smaller, but the larger the aperture lens the more options you have. So it would be the F2.0-F4.9, unless you shoot mostly at the telephoto end and that would be better with the F4.3.

You need to understand what that specification means.

Example F2.0 - F4.9
If you do not use any optical zoom the lens is rated F2.0
If you use full optical zoom the lens is rated F4.9.
The lens loses light as it zooms out.
That is a difference of about 1.5 f-stops

F2.8 - F5.9
F2.8 is one full f-stop darker than F2.0
F5.9 is 2 full f-stops darker than F2.8

F2.8 - F4.3
F2.8 is one full f-stop darker than F2.0
F4.3 is only 1 full f-stop darker than F2.8

In order of preference:
F2.0 - F4.9
F2.8 - F4.3
F2.8 - F5.9

In addition there is another specifications that is not shown.
A lens has a device inside for stopping down the lens further (making it darker)
Depending upon the lens, it could be stopped down as far as F8, F11 or F16

Full f-stop chart: 1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11, 16

There are some lenses that are rated just F2.8 which means, it does not lose light as it is zoomed out.
They are more expensive.

Here is a link to more information of aperture:

http://en.wikipedia.org/wiki/Aperture