Well, well, Mr. Galt: "There are two sides to every issue: one side is right and the other is wrong, but the middle is always evil."
Much as absolutism makes for simple priorities, applying these general principles out of any context is going to make you wrong no matter what you choose. As in game theory, where mixed strategies often defeat any individual strategy, the best, the worst, and the middle all encounter their uses in different spheres.
Personal possessions? I'm fine with the best or the worst, but not always. For instance, I could buy one of the world's most powerful supercomputers if I were rich enough, but I'm fine with my MacBook Air.
Also, try political or religious thought. I typically prefer a moderate liberal or conservative to a fire-spitting Tea Partier or an ardent communist. I also prefer secular humanism to, say, fundamentalist Bible-bashing or virulent atheism.
I propose a different criterion: the right philosophy for the right context.
> I could buy one of the world's most powerful supercomputers if I were rich enough, but I'm fine with my MacBook Air.
A world class supercomputer isn't the same category of good as a MacBook Air. Most laptop owners would feel worse off in some aspects of the trade, as they would no longer have a portable computer to travel with.
If a Macbook Air nets you the most personal utility from a portable computer, as opposed to a 2003 Thinkpad, your ownership could be used to support rather than negate the "best or worst" heuristic.
A better example to support your position would be if you owned the 2011 model instead of the 2012 model of the same laptop. You could declare ownership of the newer models always nets you greater utility, but that upgrading every year isn't worth the opportunity cost, and that it would be silly to find "the worst" laptop to downgrade to every-time you decide to forego an upgrade.
True, I gave a suboptimal example, in that the Air may actually be the best tool for the job. However, as you said, we can easily adjust the example so that it demonstrates a suboptimal possession with diminishing returns on improvement. For instance, take my iPhone 4S. I could buy a 5 because it is "the best," and a solid improvement on my 4S, but I have no pressing need for it. While I would benefit from a usage perspective from upgrading, I can still place plenty of implicit trust (Dustin's term) in the 4S for the ways in which I value it. By not upgrading, I can take pride in the suitability of my choices to my needs, rather than in the shininess of my devices.
Of course, that doesn't cover the pressure of choice detailed above by the "satisficers". To paraphrase Dan Gilbert (Stumbling on Happiness), adding more perfect options makes maximizers more stressed and less happy about what they do choose. Again, I prefer to place implicit trust in the quality of my selection process - its capacity to find me something good enough - rather than always in the quality of what I own. That latter threshold changes with the circumstances.
> Personal possessions? I'm fine with the best or the worst, but not always. For instance, I could buy one of the world's most powerful supercomputers if I were rich enough, but I'm fine with my MacBook Air.
Well clearly, it's about what is best for you, not the best in general. For you, the MacBook Air is probably the best option. The fastest car in the world is not the best road car. The most powerful computer is not the best for surfing the web and running your ruby scripts.