Welcome to the forums firecracker69.
The Pioneer 206 is a very good blu ray drive, and the one I would choose from the lists at either of your regular shopping sites, though the LG's are also good drives. Neither shop seems to have the newer LG 12x drives.
12x refers to maximum writing speed for the drive. Most media is rated at 4 and 6x however, so top speed is not really all that important. I personally would never burn single layer BD-R disks faster than 6x, and with my older LG model, I burn at 4x most of the time.
Compatibility of your burned disks depends on the capabilities of your player/reader combined with the quality of the disks you choose and possibly your burning speed. So, the drive that you burn with is down the list of things that might cause problems in playback. It is possible to get some bad combinations of media and poor support in the firmware of the drive, which can lead to bad burns, so we recommend sticking to certain types of blu ray media that are known to be good.
The brand we recommend most often is Verbatim. Be aware that Verbatim makes two types of BD-R disks, and I recommend that you only use the regular, inorganic dye Verbatim BD-R. The other type is designated LTH, and uses an organic dye. Some players/drives are not very compatible with the LTH type, so unless you know for certain that all the equipment you intend to use with these burned disks are compatible, stick with the regular type. Here is an example of the good ones at Amazon.uk: http://www.amazon.co.uk/Verbatim-43689-BD-R-25GB-Spindle/dp/B001G0N4TM/ref=sr_1_1?ie=UTF8&qid=1323717789&sr=8-1
By the way, be careful not to buy a drive listed at either site that is designated as a BD ROM. It will be a combo drive, that burns cds and dvds, but not blu ray. It will only read blu ray.