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One of the things I love about it is due to alot of the framework that came from NetBSD. Because of the wonderful driver architecture, damned near all supported hardware can (and do) have that support built into the generic kernel, without taking up that much space.
Although it's hardly difficult to make FreeBSD (for example) load an appropriate sound card driver on boot, the simplicity of having the support built-in is refreshing; one less tweak to make upon doing a fresh install.
In a few years when OpenBSD has kernel support for threads, and a unified buffer cache, I'll be hard pressed to recommend anything else to someone who needs to use a Unix-like OS.
That said, it's best feature, as always, is security through quality control. What a concept! ;^)