Depends on the genre of music you're doing, other uses and current gear. Here's mine in order of favorite:
EV RE20: Easily the best of this list. Big, sturdy, deep, natural sound with good high end. Great for 70's rock, jazz. EQ it moreto get hiphop or hard rock. Also good vocal mic, bass amp, guitar amp. Thickens things.
ATM25: Natural, takes EQ well. Good on Toms and other percussion as well.
AKG D112: Solid sounding but not as solid as the RE20 or ATM25. Good on bass amps.
Shure Beta 52: Very scooped EQ - I'd only buy this mic if I needed a kick mic for live sound in addition to recording. Pretty cool on bass amps. Think of it as already EQ'd - but that means it doesn't take EQ as well as the others for recording purposes. Has that basketball bouncing sound - kind of hollow - which can be great if you're going for that.
You can't really go wrong on any of them. If you've got $300 the RE20 is a no-brainer. I haven't used the D6 but I gather it's got a deep lows and particularly extended highs = metal.