I have never used the RE20, but I have used all of the others.
I personally love the Audix D6. I wish I owned one. It is a very "user friendly" kick mic that doesn't change it's character that much when you change placement the way the D112 does.
It is not a "character" mic the way that the Beta 52 is.
If I owned a studio and was recording a lot of different types of music and I only could have one kick mic, it would be the AKG D112 because it sounds very different depending on placement.
As a working drummer, I want the D6. Some jerk in the club can move it a bit and you'll still get a good kick sound. It's a bit punchier than the ATM25 but there is plenty of lows and plenty of highs without all of that hollow sound that you CAN get from the D112.
To my ears, the Beta 52 is a raw and rude sound that is perfect for heavy rock and very little else.
It really depends on what you're after with your kick sound.
Wow, that's a pretty damn good answer. I think I might go with the D6 for versatility. How can it not sound so much different with some movement while the D112 can? Ive used a D112, and it just rocked. Not enough "click" though.
Yeah. . . Ditto. I played at a club in NC and the sound guy used a D6 and got one of the best kick sounds I have ever heard out of my bass drum. The D112 is good too.
Another sleeper option is the Peavey 520i. On 50% of the bass drums I stick it in, it sounds great FLAT. On the other 50% I have to do extreme EQ or use the D112.