LTO tape or Taiyo Yuden CD-Rs are my recommendations and what I personally use at home. And I haven't checked for a few years to see if Taiyo Yuden is still producing good stuff, but if you're paying around 25 cents per disc it probably still is. MAM-A CD-R media is probably a good bet; I don't recommend DVD recordable media, even MAM-A Gold, because it pushed CD-R technology too far.

Per sspiff, you do need to protect optical media from environmental extremes. Tape cartridges are more physically fragile (although I'm sure there's data recovery firms that'll repack the tape into a new cartridge) and also shouldn't get too hot or humid. And ideally are stacked on edge.