SSD has been the greatest and cheapest upgrades for me.
I wasn't one of those early adapters but close. When I tried out a cheap (for that time) 32gb SSD on an old laptop that used to run like 18 year old bitter dog, it suddenly came to life running like 3 months old kitten.
Since then, after some researching, I purchased mostly Intel SSDs. It's been some years now and none of them has failed on me so far.
Me not going back.
Games don't matter to me as I don't think I really have time to play games anyway. Well, I do play Football Manager 2012 and have like 2000 hours in it according to Steam.