RTX 2080 would be a good upgrade.
What is the model of your current power supply?
Jumping up to an i7 would be another thought, as there are plenty of games and applications out there that are well optimized for multicore processing, so the old school rule of having more cores or having hyperthreads not improving gaming or application performance does not apply on current or recent platforms. Even for older platforms running more modern games and applications, there will be a performance difference between same gen i5 and i7 that DID NOT exist to any significant extent WHEN those platforms were new since back then the software couldn't take advantage of it very well.
So that's another option.
PCIE NVME storage is another, if you don't already have an NVME M.2 drive.
Better mouse and keyboard?
External drive to back up all your important personal and game files? If you DON'T have a secondary drive or external storage, that you use for backups of your files and backing up system images, that is really the very first thing you should be thinking about. Nobody feels bad for anybody when they lose all their stuff because it wasn't backed up. And it happens ten times a day here.