I bought a few new writers to replace some of my old ones.
1) NEC Sony Optiarc AD-7200S
2) Liteon DH-20A4P
3) LG GH22N
For those who care,
1) I bought the 7200S to replace my Samsung 203B, for Verbatim 16X DVD-R the burn quality is the best among the three and better than the Samsung too, haven't try any other media yet.
2) The Liteon is to replace my Benq 1640 for burn quality scanning since my Benq no longer burn a disk without PO failures (even with known good media) OK drive if you use good media like Verbatim 16X DVD+/-R but bad drive for cheap media like CMC coded TDK, Memerox, Fuji, Maxell etc.
3) LG, this one is the best for DVD+R, it can burn those cheap CMC coded DVD+R with reasonable quality and very good DVD+/- R DL burner, Vertabim branded.
So I am satisfy with my combo, LG for my cheap CMC coded media, NEC for the good media and Liteon for disc scanning. Big thanks to IAN who helped to make my choices.