I agree with Kerry, if possible go for a full-size drive. Pioneer would be my first choice (preferably the M/E/XL versions which can handle BD-XL discs - in the UK they cost only a few pounds more than the restricted D version), but the LG you mention is also a very good drive.
Slim drives can be good quality writers, but as Kerry mentioned they tend not to be as reliable/durable as full-size drives. Also many USB sockets cannot supply enough power for them to operate reliably.
I have an earlier Pioneer slim drive (BDR-TD03) which is an excellent writer and better made than my other slim drives (LG & Samsung DVD writers). So if you decide to get a slim drive I would suggest a Pioneer. (The Samsung SE-506CB has some serious issues writing BD-R discs at certain speeds.)
Regarding discs, the Panasonic, Falcon/FTI & Verbatim discs Kerry mentioned are very good quality. But they can be hard to find in Europe (especially the Falcon discs) and expensive.
Verbatim also have a cheaper & more widely available range of BD-R discs labelled as Verbatim [I][U]DataLife[/U][/I] (as here & here). So far these have always been CMC Magnetics BD-R discs, which don’t seem to have any stability problems. And Verbatim should be getting the better quality batches. I have been using them for over 6 months and have had no failures - they even scan better than my Falcon discs.
If you want the Verbatim BD-R with the Verbatim MID code (like the discs in Kerry’s link), look for ‘MABL’ on the label.
(Be very careful not to buy the LTH discs by mistake. They clearly say LTH on the label, but the information given by some online shops can be inadequate/misleading.)
Other brands like TDK use a mixture of discs, so you can’t be sure what you will get. It might be good quality CMC, or it might be Ritek or Philips.