First PC : Help me finish it please

I’ve had gaming laptops for the past 10 years and I’m finally looking to build my first tower.

I have 3 non-negotiables;

1. a 9800 X3D CPU;
2. a 5070 Ti (I was originally going to just go for a 5080 but my friend nudged me towards the cheaper 5070Ti for a relatively low loss in performance; and
3. I’d like to be under £2500 so less than $3000

Firstly, I’d like to know about GPU brands. The retailer I’m looking at has Palit, PNY, GeForce and ASUs 5070Ti models (with the ASUs being the most expensive)

Should I just go for the ASUS assuming it’s more expensive because it’s “tweaked” better? Any comments on those other models?

Is there a MB, RAM and PSU recommendation to go with my CPU and GPU? Or can I free-ball.

I mostly play MMOs so that’s why I’m set on the 9800X3D so I’m really trying to build around the processor. Don’t know if this is a backwards way to do it.

Lastly just any advice for a first timer would be greatly appreciated.