There are so few differences between the formats it really comes down to what works in the units you're going to be playing them in.
I also have found -R to be a tiny bit more compatible than +R. I've just started experimenting with bitsetting, which helps compatibility a lot, but why not just burn -R in the first place instead of worrying about bitsetting??
And I think the problem isn't so much that +R's are higher quality, it's just that for whatever reason there is a lot of crappy -R media out there. (I've heard everything from "+R standards are harder to meet" to "-R sells so much more that's where the money is") You just have to be careful what you're buying, look for Made in Japan media of EITHER type (+/-)