Although there are some technical differences between DVD-R and DVD+R, for most uses there is no practical difference and either can be used.
If you need to record Copy-Once protected content on a standalone DVD Recorder, you will need CPRM capable DVD-R media.
If you use the discs for small incremental data backups, DVD+R will be better since it wastes less space per session on a multi-session disc. This is however not a recommended way to use DVD+/-R media.
If you have a several years old DVD burner or standalone DVD recorder, it might only support +R or -R, and you need to use the supported format.