It's painful every time I have to pick just one drive (see sig!) but I voted for the Pioneer 111 series, which is a very good all-round burner. It's not a particularly good reader and not a very useful scanner, however.
My second choice would be the LiteOn 20A1 series, which are better readers and scanners, but which have other quirks and are not quite as good burners in my experience.
I'm not voting for any drive I haven't tested personally, but if I had to choose a drive I haven't tested (yet), I'd choose the Pioneer 112 series which seems a good followup to the 111 series, from what I've seen.
There's a bunch of LG drives in the poll, and multiple models of other drives, but why no Sony NEC Optiarc drives?
(Not that it would change my vote)
Pioneer DVR-112L, LiteOn SHM-165P6S, Pioneer DVR-111L, BenQ DW1655, Plextor PX-760A
LiteOn LH-20A1P, Optiarc AD-7203A, Matshita UJ-840S, Sony RDR-HX910, Sony RDR-HX750