I can only speak for components, because the last time i bought a full PC was 2000.
Best Components= ASUS (because its awesome), AMD (great performance for the right price), Nvidia (nice graphic cards), Corsair (one of the best Ram producers)
Worst Components = MSI (my last MB crashed completely), Intel (wtf is up with the price?), ATI (so much problems with my last card)
For Laptops:
Best: Asus Rog, Sony Vaio
Worst: Macbook (it was very fast finished and i HATE the OS, back to W7 and Linux)