Is there a particular reason for your assessment? I surely would have ranked IBM Thinkpads at the top, though it remains to be seen whether the Thinkpads stay there now that they are made by Lenovo. Mind you, I am not saying anything against Acer - I have no experience with them, maybe they are at the top as well.
But I certainly don't regard IBM as the Cold Steel of computers. They may be mediocre gaming machines and offer little immediate bang for the buck (slower computers at higher prices), rather they are/were business machines with good long-term reliability and customer support. Our computer science research group here at university uses mostly Thinkpads and two or three Macs, and the same goes for the network admins. And last year we had an IT conference here with hundreds of computer scientists visiting from all over the world. As I was about to purchase a private notebook I had a good look at what the people were using during conference breaks - again, three out of four were IBM, the rest mostly Macs and occasionally something else. All of these people are essentially professional computer geeks who tend to be picky about hardware.
Kristofer