Out of curiosity, I had a look at the current SSD and HDD prices available in a local e-commerce site:

  Capacity  HDD      SSD
  500 GB    47 EUR   36 EUR
  1 TB      41 EUR   49 EUR
  2 TB      54 EUR   89 EUR
  4 TB      77 EUR   264 EUR
  8 TB      161 EUR  531 EUR
  16 TB     313 EUR  none

So it seems like HDDs are still more cost effective for storing larger amounts of data, as long as your workloads permit that, but for smaller capacities SSDs now reign supreme, cost wise. There's also the fact that most of these HDDs that I looked at were 3.5" but SSDs were either 2.5" or of the M.2 variety, which may or may not matter, depending on what you want to put them in.

I still think that an SSD for your boot drive is a no-brainer, but for other data storage HDDs still make sense. If the trend of affordable SSDs keeps up, that view might change in the future.