today, with dual format burner, it doesnt make any difference really. But I heard that DVD +R have better surface material and are more reliable. They are usually faster and, for what I can see, as compatible as -R. I bought a +R about 1 and half years ago because the RW speed was faster than on the -R. When backuping lots of data, then it matter. never had a compatibility problems so far and never ruined a DVD media too. as for price, well, both are equal in the store I bought them.
-Always put the blame on you first, then on the hardware !!!