None, really. There is no good or bad computer company, although some computer companies are better than others, but that changes all the time. They never stay consistent. Go to Staples, ask to open up two identical computers (same brand, same model, same price, same specs....) and I bet you that the hard drives will be different, the CPU heatsink in one PC would be bigger than the other - it all seems trivial but it isn't. It will effect your computer.
If I was to go down to Saltillo, Mexico where my Dodge pickup was made, they would be using the same basic components for each sub-model (Hemi V8s, Cummins, V6es) and minor changes are things like interior (leather, cloth) paint color, does it have a cheap CD player or a good mobile entertainment center with Sirius... see, with things like cars, you don't have a lot of room to work with in substituting and replacing components. Same with manufactured homes. They tend to stick to it - if they say they use 30-year Owens Corning shingles and a Rheem furnace and Weyerhaeuser lumber, gosh darn it, they use it. If they, for example, run out of GE refrigerators, they place an order. They don't have someone run off to Sears to buy a bunch of Kenmores.
What I'm saying is, there is no consistency in PCs. Laptops have a bit better consistency, well, maybe not because maybe Monday, the workers will slap in a no-name LCD panel when they don't give a whirl but on Friday (usually pay day) they feel generous and happy to end the week and throw in a Samsung panel. It works like that - always.