TL;DR: CPU upgrade first up to 8 cores. Then worry about GPU upgrades. This is true for either Intel or AMD users. If you game at 4k, you need both upgrades.
World of Warcraft is more CPU bound than GPU bound, with the exceptions being if you are interested in ray traced shadows (Windows client only). As of the 8.1.5 patch, WoW uses an enhanced multithreaded engine, which means that a CPU upgrade will do more for you than a GPU upgrade will, with the exception to that being if you have a bottom of the barrel GPU (1050 qualifies as that, especially the gimped versions with slower buses).
With AMD really putting Intel through the wringer with its superb multicore performance to cost ratio, there’s no reason not to go that route vs. Intel currently, especially since AMD has PCIe 4.0 now while Intel does not. That said, IPC is still king of the hill and as far as WoW is concerned, an 8 core Intel CPU will beat out a 16 core AMD CPU since even though WoW is multithreaded now, it can’t utilize that many cores and Intel’s higher IPC wins with the number of cores WoW can use currently. But when you’re on a budget, AMD ticks off all the right boxes and comes close enough on the IPC front to give you power that’s easily good enough for WoW.
For the GPU side, if you’re playing at 1080p, the GTX 1050 will be OK, though not fantastic. The 1060 wins there as the defacto 1080p card in the Pascal range for nVidia. Any 20xx or 30xx card will trounce it though even on the low end (the 30xx series will make the 10xx series cry uncle by comparison).
The biggest elephant in the room right now that’s driving CPU upgrades as being better than GPU upgrades is the crypto currency mining that’s making GPUs nearly impossible to find again. I want a 3390 so badly but I’m not paying $2k for one, and that’s assuming I can even find one (I can’t, really). Hell, it’s hard to find even the lower tier GPUs right now on either side. What is available, if you can find it, is so grossly overpriced that it makes no sense to buy. Neither AMD nor nVidia is doing enough to combat mining farms and scalpers. So for the foreseeable future, that GPU upgrade you were considering or just bought is the best bang for the buck you can get for WoW.
Note: If you play at 4k and/or want the absolute max draw distance at 1080p/1440p, you will need a better GPU. Draw distance and clutter are the two biggest GPU bottlenecks in WoW. Spell particles, though flashy, rely primarily on CPU horsepower, so beefing up the CPU is the primary priority if you do dungeons and/or raids constantly.
One hugely grand irony in all this is that by failing to shore up supplies or force vendors to sell to legitimate non-mining farm buyers, nVidia and AMD have left the door wide open for Apple to slip by them with their new ARM SoCs, and if Apple’s graphics capability makes a major leap in the near future, it may cost the others a lot of lost opportunity. And make no mistake, ARM is efficient. Very efficient. So much so that Microsoft is working on an ARM64 version of Windows, potentially with the same Rosetta transition layer technology Apple uses for early adopters of ARM64 CPUs. I’m not a fan of Apple’s tactics, but they’re damn good at throwing a monkey wrench into established markets’ engines.