The 4090 is mega overkill for this game, even at 4K, and it’s a huge power hog/heat generator–but with your budget this is likely not a concern. Your CPU will make the biggest difference, in which case…
Get a Ryzen 7 7800X3D for CPU (not the 7950X3D, etc, since those aren’t better gaming CPUs), and a decent motherboard. I went with a ASrock X670E Steel Legend (could’ve gone cheaper, but I wanted 4x Gen4 2TB NVMe drives for storage potential).
Edit: It should be fixed now, but there was a problem with mostly ASUS, and some cases with MSI motherboards frying 7800X3D’s on the default BIOS from overvolting them out of the box. This has, to my knowledge, been fixed, but I went with ASrock anyway, since I heard great things about them, and 0 reports of this happening on their boards. Quite pleased with my choice, but generally you just fire it up and flash the BIOS anyway, so you should be fine. I just thought I’d give this tidbit if you concerned, but I wouldn’t recommend ASUS with how unapologetic they were about this situation at the time.
CL30 RAM clocked to 6000 mhz via XMP profile, etc. (I went with 2 x 16 gigs of Corsair Vengeance, make sure you go for 2 sticks for dual channel. RAM choice is preference, as G.Skill is fine, too, for example.) Grab some NVMes to install onto, and have WoW and your OS on separate drives. Not a big difference these days, but with that budget why not go all the way with trying to optimize the hardware configuration.
I, personally, don’t advise going Intel CPUs right now, unless you have a specific use case for them. They run too hot, and eat too much power, and they only evenly match the 7800X3D at best. The 14k series is just the 13k but hotter and less energy efficient, only being negligibly better in SOME workstation tasks. Furthermore, their sockets require a new MOBO pretty much every single cycle, and because of how hot they run they require a lot more powerful cooling solutions.
Overall, I’m happy with my build. I’m running on a 6700 XT GPU and 1440p. I plan to get a new GPU at some point, but if I ever run into framerate issues I can just turn on AFMF and cap my monitor to 120 FPS (half my refresh rate) and have a stable 240 experience.
If you’d like some resources to research hardware performance before locking into any recommendations here, I recommend:
Gamers Nexus, for specific benchmarks and a LOT of technical info, and
Daniel Owen or Hardware Unboxed for gaming/GPU benchmarks (does not include WoW, though, but has more modern games in the graphics department).