A Pioneer, LiteOn, Samsung, HP [rebranded LiteOn], or Sony [rebranded Samsung] external drive will be good.
If you’re using Verbatim or Taiyo Yuden media, I’d also say you can get an LG, just making sure to watch your write speed.
Most any recent external model from these makers [18x or 20x drives] will be good choices, except for a Pioneer drive with LightScribe–these are made by Asus for Pioneer and don’t have the best write quality.
My personal choices would be the LiteOn DX-20A4PU, Sony DRU-840U, or HP DVD Writer 1040e, as I’ve had all the internal variants of those drives and like them.
I also just got an LG GSA-E40L, and like it, but it can be picky. It is rated for 18x, but my laptop can only do 16x max with it. However, all its write speeds are fast when compared to others makers. My best quality with it has mostly come from 8x and 12x on Verbatim 16x and 8x media, as well as on Taiyo Yuden and Sony 8x and 16x media.
My last external experience was with the HP DVD Writer 840e, which was a rebadged LG GSA-4166B/2166B with HP’s styling applied to it. It is a 16x max drive, and could reach 16x. But it pretty much had the same likes and dislikes at the GSA-E40L has. It is unavailable now [replaced, in the long run, by the 1040e, that is made by LiteOn and is less picky].
What laptop do you have?