I see that mentioned a lot, and quite frankly I find it silly.
Yes optical discs deteriorate, but it doesnt happen over night. Typically it'll last the length of the mediums lifetime.
Doing both is a better bet. Ive had harddrives die on me and have lost TBs of data 'cos of it.
Have one or 2 blu ray discs die is a lot less painful.
Ultimately though "best" is in the eye of the beholder. Everyone who's content with the way they have things setup/stored will be convinced their choice is the best.