Hard to recommend anything specific with no budget. If it were me, since you say you're OK with the RAM, just upgrade the GPU for now because it's kinda pointless to put much money into upgrading your DDR3 platform with a CPU you can't use on a current DDR4 platform.
You can pretty much rule out a 1080 due to prices shooting sky high when the 2000 series launch was kinda underwhelming regarding no RT or DLSS support yet. You can still get a 1070 for $300 - $320, but it's not necessarily going to be powerful enough for what you want (depending on games, which you also didn't mention).
If you're still OK with AMD, you could maybe wait for the 7nm Radeon VII GPUs, but that may be a fool's errand, as some are speculating they only plan to release the mainstream one's this year, and the enthusiast ones in 2020, and who knows what they'll be priced at.
Right now you can get a Vega 64 (1080 equivalent) for as low as $400 for a reference blower style card, or $522 for a aftermarket cooled open box card. PSU wise you need 500w for a 1070, and a whopping 750w for a Vega 64.
Supposedly Nvidia might launch a 1100 series, but no confirmation yet. It's kind of a bad time for upgrades with high prices due to being in between releases and a rather haphazard 2000 series launch.