Both are good burners, not easy to say which one better is.
I vote for the Pioneer, because it´s the newer one with better specifications like DVD-R DL, DVD+RW 8x and DVD-RW 6x.
The XL-versions from Pioneer can rip DVD-Video at full speed, DVD-R/+R at 12x max, DVD-Video DL at 12x max. The 109 is very slow, max. 5x
The Pioneer has good writing-quality with the most media, but burns some 8x-media and newer 16x-media at lower speeds (but maybe this would be fixed with new Firmware)
For important data I would never use Ritek. The 8x DVD-R can be burnt at high quality with many drives, but in the c´t-test it don´t has a good stability and is not to recommend for backup´s. The 8x DVD+R don´t have good quality with many drives, also not to recommend
Use Taiyo Yuden, Ricoh or Verbatim for backup´s.
Benq DW 1640, LG GH-20N, Pioneer BDR-208
Crucial M4, Sandisk SSD, Plextor M5S, Sandisk Ultra Plus, OCZ Petrol 256GB