The Field Navigation course at our technical college (a requirement for Forestry, Fishery, Wildlife, Environmental and Natural Resources technicians) has always recommended either the Suunto MC-2 or the Silva Ranger.
But when the campus bookstore's supply of Silva Rangers came in this year, many of them had bubbles. Of the rest, several developed the bubble quickly, or soon had broken declination adjustments. There have been similar problems the last couple of years with Silvas. Meanwhile, the older Silva Rangers (European made) have proven reliable over decades of use by college staff. If you buy a Silva, buy an old one. The Suunto MC-2 is still a solid, reliable compass with great features, and I've not heard of anybody having trouble with one.
The sighting mirror on a compass (aside from its multipurpose use in first aid and emergency signalling) allows great precision in field navigation and mapwork. (Whether you need this depends on your intended use and terrain, of course.) Using your dominant eye (important!), hold the sight to the landmark at eye level, and look at the compass dial in the mirror. This lets you see both landmark and azimuth at once, in perfect alignment. Should you find yourself navigating in conditions of reduced visibility or short sightlines, the ability to locate a point to walk towards (a treetop, for example) so precisely can, in the long run, save a lot of course correction. And if you are trying to put something on a map, the more precision the better.