Garbe is one of the pipe makers most extolled by Marty Pulvers, along with Former and Barbi, and I'm sure that makers such as these do make a better pipe. But in the end we discuss the flavors of tobacco in the smoke, and as long as the drilling serves to deliver them through a stem that is comfortable, I'm not convinced that one pipe can be said to be better than another. These are the main considerations, but I can agree there are other factors in play. No one wants to smoke a pipe with an abominable design, and if the smoker clenches, he needs something light.
But then we come to claims of quality that cannot be substantiated. Very few in a blind test could tell whether they were smoking 10-year air-cured Castello or just off the vine Savinelli. And as long as the draw was open, few could tell whether the pipe was drilled to 3/16s or more conservatively. And so on.
I think the most admired pipes are those that appeal to a common denominator of a shaping aesthetic, such as Former. Then too fit and finish can be made virtually bulletproof. But beyond this and the considerations above, I think it is the pipe community that creates superior value out of a specific characteristic; that is, when we smoke a pipe with well-cured briar, we impute the superiority of the wood to that smoke. But I argue that hardly anyone can taste the difference. It makes sense to say that briar without resins would contribute less impurity to the burning tobacco, but can anyone taste this, and if they cannot, then why are we talking about it as as characteristic of a superior pipe?
Similarly we say that pipes with thick walls or with a longer shank/stem smoke more coolly. Who's measured this? Who says this other than pipe vendors?
We also have our preferences for the shape of the bit and the bit draft and say that a more open bit is better. What is clear in this matter is that we have preferences, but I'm not sure that a bit draft clearly only opened by a machine smokes any less well than an elaborately-shaped and exquisitely opened bit by Kevin Arthur. I like this bit a great deal, and that is part of its allure, but I can't really say it is any better.
We don't/can't measure pipe smoking, but we are full of opinions about the quality of pipes.