I personal prefer dvd-r.
im not expert and i might be wrong, but the differences include:
-dvd-r is cheaper, but generally burns slower
-dvd+r claims to be more compatible and is supported by MS and sony
-dvd-r is actually more compatible according to Slashdot
-dvd+rw is better than dvd-rw, more compatible, multi-session, etc.
but really when it comes down to it, dvd-r media is at least $.50 to a $1 cheaper than dvd+r... so economies of scale and that crap..go for dvd-r...or shell out the cash and get a +/- burner. Do people use RW regularly?