For builds in the 1200-2000USD range, there is no better CPU on the market ATM than the Ryzen 1700X. It's a price to performance baby. Intel isn't behind though, if you're pushing more money, Intel has you covered.
There is also really macgyvery shit you can try like a Sandy/Ivy bridge server machine. A couple of them in a dual CPU board will wallop a Ryzen in multithreaded tasks any day of the week. You can also get a barebones server type thing. I saw one the other day with 4 4/8 core/thread Xeons with 32GB of RAM for 200USD (60USD Shipping) Throw the rest of your money into a kick ass SSD and GPU, and you've got yourself a beast of a multithreaded machine. Just add Linux or another OS that can take that many CPU sockets.
It does heavily depend on what task is at hand. A lot of higher end CAD, video editing, and 3D modeling can take GREAT advantage of loads of threads and cores, but for gaming, I'd say stick with Ryzen as the single core performance is a lot higher, and for gaming tasks that rarely take anything but 4 threads, Ryzen will be your best bet. Intel IMO is currently going to pull a rabbit out of it's hat to do something about Ryzen, so don't grab anything brand new from them.
But after you have figured out use, you need to figure out price. What is the monetary number you are working with? That's basically the deciding factor for what you get. If money is not a problem, then sky is the limit with computing, so there will always be a number.