Depends what your storing on it. All my drives except one are either SSD or M,2. The one that isn't is a 3TB sata 6 which is from a previous build and I use it to store saved game iso's and the like, mainly stuff that doesn't need to run or execute.
I found a long time ago that a mechanical drive wasn't fast enough for my Newsgroups downloads. The download would keep pausing as the old hard drive couldn't keep up with my download speed.
In that case I definitely needed an ssd.