Dell, Toshiba (extremely slow, even when I replaced Vista with Win 7), and Lenovo are on my blacklist. Just like smartphones, it seems impossible these days to find a manufacturer with a product that works well. It's all about grabbing the money and running away.
I have different experience. Toshiba Satellite A35 lasted 7 years. About right.
Many Dell Inspiron I have are still fine after 7 to 8 years. Battery needs change after 3~4 years. Battery works like tires. Can't blame them for that. No power adapter issue in my case.
Alienware 18 cost me a fortune. Some people may think it's overkill and over-spent. It's running reliably for me with less wait. Suit my need just fine.