I am realizing that while my old computer does a lot of things very well it just can't keep up with Blender 3.0 or higher. Gets crashy a little too soon.
When I shop for a new computer, what I want is:
A graphics card
Lots of RAM
Good keyboard feel
A numeric keypad on the keyboard
Not too expensive.
I mean. . . the most of all of those you feel like spending?
I'd say video card first. Probably NVIDIA as Blender's support for NVIDIA's features seem to be ahead of AMD's. (Do your research and look at bench marks and price/performance/watt)
Ram, definitely.
After that, a good multi-threaded processor.
An SSD.
Graphics card and CPU are probably the most expensive and variable bits of the build.
CPU VS. GPU considerations
https://blender.stackexchange.com/questions/47598/should-i-buy-a-better-cpu-or-gpu
Also, be aware of the memory on the video card itself as that makes a huge difference once you get into larger scenes.
Good Luck!
Edit: You probably already know this, but if you're building it yourself and not going the pre-built route make sure that your socket/processor/motherboard/memory, etc. all line up. Also, don't skimp on the Power Supply, or a decent case with nice large fans for cooling!
I'd say just get a pre-build one. I've gone through so many headaches with a clone computer. I've also gone through laptops and those aren't as powerful for doing 3D. Last time where I just went and said give me a powerful one capable of doing 3D and give it to me already built, I don't want to start having to disarm it changing stuff around and then the computer misbehaves.
I always start on top, see what would be a killer computer and of course it will go over my budget but then I can start rolling back stuff until I reach the price I can pay and that's my computer right there and then. We all know an SSD is a must, that 32gb of ram is a must also, Nvidia, better if GPU is in the 30x0 series, with lots of vram, CPU last gen, and so on and so forth.