The Shure KSM44 is a reasonably affordable (about $800 new) condenser mic that can be used effectively to record a wide variety of sources. It's a multi-pattern mic so it can be switched easily between cardioid, figure-8, and omni-directional which is part of what makes it versatile. But the real key to it's versatility is it's neutral frequency response which means it doesn't impart a lot of "color" into the recording.

Certainly in some instances you may want that "color" but in others you may not. If you don't have a huge amount of mics to choose from (and most people with a home recording studio do not) then you'll want to have your primary mic be one that doesn't have the tendency to hype certain frequencies because that may make it unsuitable for many recording tasks.

The Shure KSM44 can be used effectively for recording a wide variety of sources (including acoustic guitars and vocals) and it's a very sturdy mic that can withstand a lot of wear and tear without losing any of it's clarity.

It's a recommended mic in the "Home Recording for Musicians (For Dummies)" book and the author says it's good for drum overheads, percussion instruments, acoustic string instruments, and as a room mic.

Articles on the KSM44

"For Recording Vocals & Acoustic Guitar"
"Perfect Condenser Mic for Home Recording"