IdBuRnS... I've used the Toshiba, Samsung, and LG drives in various computers that I've built for others. It honestly depends greatly on what you want to do with your drive. Personally, since I was building a SFF that was going to sit on my desk, I chose the Toshiba, because in my experience, its the quietest. Its not the fastest, though. The LG is a FAST drive (esp. with burning speed)... but its relatively noisy (about the same as a Lite-On). If you don't care about noise (or its going to be sitting under your desk), go for it. The Samsung that I put in was a specific request by a friend--he's happy with it. Its a bit faster than the Toshiba that I use, and a bit louder. Kind of like a compromise.
Plextor DOES have a good reputation, but I can't say anything about it--I haven't used it.
Good luck!