What is your next upgrade?

I'm probably going to pickup some more RAM next, I've currently got 16GB but I'm planning the leap to 32GB.
However if I do that I'm spending a fortune on more DDR3 RAM, which might not be a smart choice because I don't know long long I'll have my rig before replacing the whole lot. Which would then probably need DDR4...

I was also considering getting some more storage. My 6TB of mechanical drives are currently full, and so are my SSDs. But I'd get that in a separate NAS unit more than likely.
While were on the topic I might as well mention my most recent upgrade. I made the step from 1080p 144Hz to 1440p 144Hz. It's lovely, text is finally nice and crisp even on a 27" panel. < 3