Best long term solution for archiving and preserving photo and video : dvd, hard drive, other?

It seems to be difficult to get to the bottom of this question.

I have a large collection of Hi8 tapes that I am putting onto hard drives through my Mac computer.  My concern is maintaining the integrity/quality of this video over time--30 years.  Is there degradation or loss of quality over time with a dvd and a hard drive?

If I copy a hard drive containing video and photos to another hard drive is there a loss of quality?  If ultimately hard drives ware out, then I will need to copy the video to another hard drive.

Are the newer solid state drives better and longer lasting than convential hard drives?

Should I be storing these hard drives and dvds in a safe