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I've done a good chunk, but I haven't found a good source for tape drives. Mine I bought second hand and it overheats and I found that it actually fails it's testing, so be extremely weary on buying them. I did LTO-8, but I've been waiting for years now for them to drop in price. (I probably did the same comparisons as you, TB/$ pricing).
The biggest thing is to make sure you support LTFS. I've tried multiple softwares, even down to tar, but LTFS will make your life simpler. It acts as a simple mount in linux, you just copy and paste.
Tapes themselves are all pretty much the same. I buy them new, never used, just like HDDs, and they're cheap enough that who cares. Note that the compressed sizing will never be reached. Remember that most ISOs are already compressed, and most of your data is already compressed, you can't compress compressed data, so it's pretty much a straight shot.
Tape can be a great option, I keep mine in a safety deposit box, fully encrypted. However getting it all set up is a pain in the ass. If you find a good drive at a good price, let me know.