PC hardware is unique because every part is both a product choice and a constraint on the rest of the build. Spec sheets help, but they rarely tell you whether a graphics card will breathe inside a compact case, whether a motherboard gives you the ports you actually use, or whether a processor needs more cooling than your case can comfortably support.
A good build starts with the job, not the most expensive component on the shelf. For a gaming PC, that may mean putting more of the budget into the graphics card while choosing a processor that keeps frame pacing steady.