There are tools in the world that can be a bit on the pricy side, but are worth every penny. The German-made Knipex 10" pliers wrench is one of them. This single versatile tool can replace just about any crescent wrenches and/or channel-lock pliers you've got in your kit. (Maybe you can use those old things as "loaners" while keeping the best tool for yourself ?)

With the press of a button, the lower jaw of the wrench can be adjusted between 17 settings, each of which allows you to squeeze the handles for a firmer grip. The leverage-multiplying mechanism (10-to-1 ratio) makes this easy and comfortable to do, with no wrist strain at all.

The two jaws are always parallel to one another no matter how wide you open them (1¾" max), and they sport smooth surfaces rather than serrated so they won't damage bolts and whatnot. This full-contact grip allows them to apply a great amount of torque for their size, and they even have a quasi-ratchet action that can come in handy in confined spaces.

The company's promo video shows it in action:

There's simply no substitute for a tool like this. Get one for $51 on Amazon.