NZXT tried to charge $1000usd each for 3 of their ssds. I was like uh nopeIf you plan to go really custom and money isn't a thought with it than MainGear and OriginPC are the two I have done upgrades in and saw quality. Most importantly I saw they actually put the parts into them that you paid for. You would be surprised how often these pre-built places tell you they are putting in an "Asus Strix 3090" and you end up with the most off brand 3090 money can find off ebay (you remember, back when video cards existed). The guys that are most notorious for that are IBuyPower and CyberPowerPC from my experience.
But if you are buying off the shelf systems already assembled and looking for best bang for the buck then you probably are going to be looking at iBuyPower and CyberPowerPC. The systems will work. They will have powerful hardware. It just won't have greatness but lets be honest greatness isn't often required. Just expect them to run a little hot. Expect them not to have a ton of effort put into them. Know that the reason its often a great deal is not a lot of elbow grease is being put into them.
If I really had to recommend one it probably would be BLD by NZTX. The parts will be what they say. It is just customizable enough to not screw it up if you are a novice. The price isn't insanely marked up. Now it won't be anything flashy but it will get the job done. I would say it is the closest thing you will run into that has that "home built" feel to it while coming out of a box. So everything will be easy to work on and repair/upgrade when needed. Unlike a lot of these places that use custom cases, parts, or stuff so much shit into a little case its often a nightmare to work on.