I basically use Verbatim DVD+R blanks. Sometimes I also use TDK and Sony, but Verbatim is my #1 choice.
In case you are considering 8.5GB dual layer blank DVDs, then the answer is simple... Verbatim only, and only those manufactured in Singapore. To play in a standalone DVD player, you must burn at the DVD's rated speed of 2.4x (or 8x for the more expensive blanks). The 2.4x blanks can be burnt at up to 8x and it will work fine in a PC DVD drive, but it will not fully play on a standalone DVD player; I think there are read errors on the 2nd layer. Therefore, burn at 2.4x only.