DVD+R DL is better supported by burners and reader devices alike, not to mention it's superior to DVD-R DL. For example, you can't change the layerbreak position on the DVD-R DL standard, and this is needed for DVD-Video/console games/navigation discs/etc. Since less people use DVD-R DL, the manufacturers don't tweak much their burners' firmwares for this type of media, and, in the end, you get low quality burns on this media, if they burn at all.