which is the best version of nero for windows XP professional

You'll only be able to buy the current version unless you can find a legal earlier version online.

The current version is Nero Burning ROM 2014 but for Windows XP you'll need to install Service Pack 3 (SP3): http://www.nero.com/enu/products/nero-burning-rom/system-requirements.php

If you want the bloated "bells and whistles" Nero instead of just CD/DVD burning, that's here:
http://www.nero.com/enu/products/nero/system-requirements.php
That also requires Windows XP Service Pack 3

Please bear in mind that all Nero products are 32-bit only, but they will of course work on Windows 64-bit.