I voted for no particular preference. As long as they’re good quality media I find that both types work ok for me.
Long time ago when I owned an old Liteon LDW541 then I prefered +R because they just seemed to work better than -R in those older liteon models. Later when I first got my Pioneer DVR108 I switched to -R, partly because the 108 slightly prefers -R but mostly becasue it couldn’t booktype set which made -R the most compatible media (+R wont even play on my home player unless it’s booktype set to -rom).
Anyway these days I’ve got a few different burners and can use +R or -R so I just buy whatever I can get a good deal on. I know that technically +R is supposed to be superior but personally I don’t find any real difference (particular burner preference not withstanding).