Technical blabber aside, - and + are essentially the same. Technically, +R media are superior. Compatibility goes for -R however, since you don’t have to bitset them and are universally accepted by any player ever made (-R DL discs are a different thing altogether) - there are standalones that won’t play non-bitset +R media (some older units won’t even accept +R discs!).
I personally go for -R for DVD-Video and +R for backup data, but since I have bitsetting writers and some of these drives write better onto +R media, I sometimes find myself writing to +R more. +R media in some cases are more expensive though, and actually has a bit less total capacity as compared to -R media (just a few MBs though).
If your focus is for DVD-Video, DVD-R will provide the best compatibility and isn’t needed to be bitset (since there are some drives that can’t bitset properly). If your drives can bitset (and your focus is still DVD-Video) and you want to feel secure in the technical superiority of +R media, +R is for you. If data is your thing, -R or +R has virtually no difference.
If you’re anything like me, you’ll collect all the good media you can find, be it - or + DVDs, and use them at your whim. Burn on!