I'd go a little far and say be generous in your PSU. A bad PSU has the potential to fry even the best components you carefully chose. Regarding brands, there's really no mystery - just avoid the obviously cheap chinese generic brands. Even manufacturers considered mainstream (like Gigabyte) make pretty decent hardware that will last long enough. Asus, Corsair, Samsung, SuperMicro, Intel, AMD, Hitachi, XFX, G.Skill, EVGA, all are pretty good brands which provide more than enough of a good support.
That's really easy to buy parts and build a PC, but if you don't have enough confidence/knowledge to do it, you can buy a Dell or Lenovo. You're just paying a little more for the same-ish performance.