It’s a format war, like VHS and Beta back in the old days, but much more confusing because the discs, players, and recorders look almost identical.
There are two main camps of disc makers. One uses the dash (-) in their names, the other uses the plus (+). There are record-once ® and erasible (RW) disc versions in both camps, so you end up with four differnt disc types: DVD-R, DVD+R (both record-once), and DVD-RW, DVD+RW (both erasible).
(There is also a fifth type of disc, DVD-RAM, but it is rarer.)
I recommend getting a recorder that handles discs from both camps. Such are well below CAD 300 in Toronto.
But if you’re looking at compatibility with the installed base of older players only, DVD-R has the edge: more older players will play DVD-R than any of the other formats.
It’s also a good idea to check the specs on any DVD players and drives you already own, to see what they can already play.