I can't really make an informed comparison here (I wonder how many can, since few of us can afford to buy every drive out there and do direct comparisons). I will say, however, that subjectively my 48x Memorex 48MAXX / LiteOn LTR-48246S doesn't seem that loud. It is as quiet or quieter than my Yamaha 24x CRW-3200EZ and several CD-ROM drives I have lying around (NEC, AOpen and, yes, LG). I really don't think it is particularly loud for a 48x drive.
On the other hand, I will admit that my LiteOn 166S DVD-ROM drive does seem louder than other drives when going full tilt on data discs. But it is very quiet when playing audio CDs, DVD, VCD and SVCD discs because it is smart enough to slow down to 2x or so.
Maybe the next time someone I know needs a drive I will get them a Samsung. They seem to be good quality, and I could then compare the noise levels before handing it over.