me too, I keep seeing conflicting advice, as to whether -R or +R are "most" compatible.
As far as I can tell neither are 100% compatible with domestic players (I guess this is due to the vast number of £40 korean players and obscure player like PS2?).
Perhaps the best idea is to buy a burner with all formats covered (LG GSA 4040 is only £130 at DABS) - and then you can try either disc in the player(s) you plan to use??.