Suunto, a Finnish company with a great track record of quality compasses, makes a variety of models. Here's an overview of three that should suit the needs of every outdoor traveler.
Generally speaking, it's best to choose a compass that has adjustable declination, which I think is the most important feature. Having adjustable declination let you measure bearings to true north, and thus eliminates any confusing backcountry arithmetic such as adding or subtracting declination.
Having said that, I realize that a compass a piece of gear that some people will rarely use and want to save a few bucks on. So. I'm going to suggest three different price points, think of it as good, better, best, so you can choose the one that looks best for you.
Good - Suunto A-10 compass
This is a bare-bones compass, but still a quality instrument. It has what is called “fixed declination”, not adjustable declination. But, everything else about it is solid, including the nice curved base plate which ergonomically fits in your hand, always reminding you of the proper and to hold the compass.
Here’s a trick to deal deal with magnetic declination on this compass. Carefully draw a line with a medium black sharpie pen from the center of the compass to your local declination on the outer dial. Now, when you want to take a bearing or measure a bearing, you line up the red magnetic needle on this pen mark, and not the red orienteering arrow. Of course, this only works if you stay in your local area. If you travel far away where the declination might be different, you may have to erase this pen mark with a little rubbing alcohol or nail polish remover or some other solvent, and draw again. But, it's one option for the frugal climber.
Cost: about $16 (Oct 2018)
Better - Suunto M3 compass
The Suunto M3 is my personal favorite, which hits the sweet spot between having all the features you need, and none of the ones you don’t.
Here’s what I like about it:
long baseplate (for taking accurate measurements from a map and drawing bearings on a map, a long baseplate is helpful)
ergonomic design (the curved part fits your hand, eliminating the common mistake of having the “direction of travel” arrow pointing at you rather than your objective)
low cost (about $15 less expensive than a comparable compass with a sighting mirror)
simple and sturdy (fewer moving parts and hinges mean fewer things that can go wrong in the field)
lightweight (no sighting mirror means less weight)
A few words on sighting mirrors . . .
But what about compasses with a sighting mirror, you may wonder. Don’t offer greater precision when taking a bearing? The short answer: Yes, they do, but for almost all backcountry uses of a compass, you don’t need this level of precision. If you’re doing field mapping or walking a straight line when on a search and rescue team, then the slight increased precision of a mirrored compass might be justified. But for the vast majority of the simpler backcountry uses of a compass, like taking a bearing to an object and then either following it or plotting the bearing on a map, the +/- 2 degrees of accuracy you can get with baseplate compass works just fine.
Also, consider that a mirror compass LACKS most of the good qualities listed above.
Most mirrored compasses:
are not ergonomically designed
have more moving parts that can break
I have used my Suunto M3 compass to take a bearing from a map, follow that bearing cross country for more than a mile, and hit my precise objective . . . at night. With a little practice, you can too. Don’t throw away your mirror compass if you already have one and like it, but if you are looking for a compass to buy, the Suunto M3 or similar model is a better choice for most users.
Cost: about $30 (Oct 2018)
Best - Suunto MC-2
I know that some people will want a compass with a sighting mirror and possibly a clinometer. Both of these features are found on the Suunto MC-2, which is the next model up from the M3 in terms of the whistles and bells. This costs about $40-$45. Again, I feel this model is not necessary for the majority of users, but if you want these extra features, this compass is a great choice.
Cost: about $45 (Oct 2018)