I'm using adjustable wrenches a lot aside with high quality fixed wrenches. They are far better than the reputation, which may originate from people that have used mistreated wrenches in the past or the wrong size for the application. A good wrench has a larger grip surface than many fixed wrenches and can be adjusted very close to the head dimension without lash.
So I've gathered a few during the years and take care of them. The primary use is for medium and large size nuts and bolts. It is also convenient to have a 4" and a 6" or 8" in the motorcycle tool pouch.
Here is a description of 6 generations of Bahco wrenches.
http://skiftnyckeln.blogspot.se/ The favorite is the so called Ergo-Wrench from mid 80's. The picture shows most of the ones I have.
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it comes in handy from time to time and maybe the super thin jaw version too. Ah ha ha always more tools to get.