- Caveats - These are software dev & light multimedia editing computers. By the time I get rid of one, it's had as much RAM added as possible. I've done this twice now. Would not work on a gaming rig.
Generally I'd buy midrange parts, from well known vendors, and pay a bit extra for SSD, ram, etc. Avoid anything with a small muffin fan (primarily chipsets these days), get a quality case, 140mm or bigger fans, quality power supply (a 5 year warranty is a good start). My current system is from 2015 and was a Xeon E3-1230 v5, 32GB ECC ram, GTX 1070, and a M.2 NVMe. The E3-1230 was cheaper with ECC then the similar i7 was without and just slightly slower (3.2 vs 3.4 GHz). Had no problems so far, and I'm just starting to look at a replacement. Looking closely at the expectations for Zen 4 CPUs and the current Alder Lake (or follow on ). I'm definitely sold on DDR5, especially since with a 2 dimm system (128 bits wide) you get 4 channels instead of 2 with DDR4. Should be that much better at not stalling your cores on cache misses.
If I bought today it would be tough decision between the AMD 5700x (8c/16T with a 65 watt TDP) vs the similar Intel Alder Lake. I do think AMD has the edge for systems that are low power and Intel the advantage for high power. Personally I'd rather have quiet, cool, and reliable instead of an extra bit of performance that nobody will care about in a few years. I'd consider a Apple M1 mini ... if it had the M1 pro or Max. Don't think the studio is quite worth it, but I am chipping in few $ a month to Marcan for a linux port.
Before that, MoBo manufacturers even made extensive use of additional chips for networking, USB, mora SATA ports, RAID and what not, which could make the whole system more complicated/fragile (all the additional drivers!).
I nowadays try to avoid that and aim for boards close to "reference" (whatever the chipset offers out of the box).
I just never bought a very expensive video card & I can't comment on how long a good one would last. I imagine it depends on to many variables from the games you play, the settings of the games you're okay with, the card, etc..