Here's our list of compasses that offer basic functionality with everything you need -- no bells and whistles (actually, one does have a whistle). All have excellent reputations and are good quality at a reasonable price. You can spend more to get more features. You can spend less for a simple zipper-pull style compass that stays attached to your pack (but should be considered a backup compass, not a primary).
What to look for in a good compass
All recommended compasses have a rotating bezel (ring) marked in degrees, and the non-moving baseplate is marked with 360 degrees. The magnetic arrow points to magnetic north. A fluid-filled variety allows the needle to settle to its position faster than a non-fluid type. I consider adjustable declination a necessity -- the magnetic variable between where the compass needle points and True North.
Each recommendation also has a rotating bezel, as well as a ruler. You want one with a ruler in inches/mm because it's helpful for measuring distances on a map. A 1:24,000 scale is handy for use with standard USGS topo maps. All baseplates have an orientation bearing line down the middle to indicate the heading orientation (where the compass is pointing in relation to the north arrow).
A compass should always be part of the gear you pack; it's a necessity when navigating from a map.
Silva Polaris is a clear baseplate style with a ruler plus scale of 1:24,000 for use on standard topo map. This old standard has been around for decades and is available from Amazon. In fact mine has lived in my pack for over 40 years, $18-22.
Brunton TruArc 5 Compass is overflowing with features. It's got a map grid line molded into the baseplate, a magnifier for reading map details, a global needle for northern and southern hemisphere use, and a ruler. Available from Amazon, $17-25.