The unsung hero (heroine?) of every PC: The motherboard! A good motherboard is the difference between a PC that lasts for 5-7 years, and another that you get rid of after 1-2 years. Please make sure that you pick your motherboard AFTER the CPU, and the not the other way around! This list is for Intel motherboards. Coffee Lake and Kaby Lake CPUs are not interchangeable, so check CPU compatibility before purchase.
Please note: The best deals are dependent on rebates. Such rebates are reliable, but only if you follow the instructions exactly and submit everything on time, so better be careful!