I’m a fan of Fusion. If ones budget is limited to HDD prices, then it’s a huge improvement over an HDD-only machine for not a lot more money. No, it’s not as good as pure-SSD, but “nearly as good” is still pretty darned great.
The real trick is whether your relative needs a 1 TB HD, or can live with a 256 GB SSD? If they already have 500 GB or more of stuff on their current Mac/PC, then the work of whittling things down to live with the 256 GB has to be considered, as does the work of managing the more limited storage on an ongoing basis.
Basically, a large Fusion drive allows them to continue with business as usual, with no new management duties (moving things to an external HD, etc.). While there’s something to be said for the better performance of SSD-only, a lot of users will never use their Macs in ways that would over-tax the Fusion.
I have a relative with an HDD-only iMac, and it’s absolutely painful to use when compared to my Fusion-equipped iMac. On the other hand, I generally can’t tell the difference between my Fusion iMac and my all-SSD iMac.