I would think that tape would be better for archival storage. My experience has been that the writeable optical media does not hold up well long term.
Plus you archive on dedicated disc type for archival which is much more durable.
Expensive to buy new, but definitely not hard to get.
I paid $80 for my low hour LTO5 drive at a government auction. Tapes (1.5TB raw) are $15 each new.
There are hundreds of used drives on eBay for relatively little money.
very subjective. Anything at that price range doesn't exist in my region at all. Also consider if there will be a government auction next time your drive fails. I found just one offer for $500 now.
My personal "final straw" was also, that nothing that I was able to actually buy or afford (reasonably, so not $1000+) required me to have at least a full desktop to throw it in and often drivers were "windows only, but there should be something for linux somewhere". Simple usb makes it much smaller and easier.
As far as drivers are concerned, SCSI tape devices have been in the Just Works(tm) category on just about every UNIX-like platform (including Linux) for the last 40 years.
Everyone's needs are different. Use what works for you.