I would recommend an ssd with a storage drive, if you already have a hd, grab the ssd, if you need space instead of speed get the hd. Depends on your storage needs. An ssd is a fine addition to a computer, makes it very snappy.
I'd invite you to try play modern games with only 250gb, or 120gb at that. GTA5 is 60gb, witcher 3 is 30gb, Deus Ex HR DC is 18gb, pillars of eternity is 15gb. You'll run out of space fast and unless you really only play two-four games at a time then you're out of luck. And that's just taking into account games, nothing on downloads of personal music/video collections
Well.... for the record, i'm pretty sure MOST people only play a select few games at a time. At least I do. Especially now. Hard enough to choose between Destiny and Advanced Warfare on my PS4, or Tera and Witcher 3, among others, on my PC.