If you're looking for actual quality and not subjective favourites, I personally think you'll never get the right answer.
The truth is there are many good manufacturers out there.
So for my "subjective" favourites:
Motherboards: Gigabyte make awesome motherboards, very rarely have I had issues with them. If I am doing a high-end build, I will also consider an Asus motherboard, but never Asus for their budget range.
Memory: Heaps of good stuff, I personally like to choose RAM with lifetime warranty and heatsinks. Kingston, Patriot, Corsair, Crucial, GeIL, OCZ, and G.Skill have all given me good results. I'm sure there's more but that's it off the top of my head.
Graphics Cards: Again plenty of good stuff. Two stand out for their lifetime warranty - EVGA and XFX, I currently have an XFX and it's fantastic. Plenty of others as well that make good cards.
PSU: This is a tricky one, there are some manufacturers who have different ranges, one I will touch the other I will not, then there are good all-round companies (like Corsair) and brands I won't ever touch (like Rosewill or Cooler Master). Do some research for a PSU list, there's a few out there, followed by plenty of discussion and debate.
Hard Drive: Generally this will come down to Seagate and Western Digital, but also Hitachi and Samsung are major players. I've had good and bad experiences with all of them, but generally favour Seagate, seem to give good performance for the money. WD Black drives are awesome as well.
Optical: I've only had Pioneer personally, fantastic. But I don't do hardly any burning, done more on my Samsung drive at work than at home and it burns just fine. Lite-On works great but are really noisy in my experience.
So there you have it, just my opinions and you can't ask for anything more out of anyone. I'm sure there'll be plenty of people who disagree with me on a certain opinion, I actually wouldn't mind hearing them because it all comes down to everyone's experiences with the parts anyway. I just keep choosing the same parts that keep working for me. And of course avoid the parts that keep stuffing up on me.