This is just a preference post but it might help someone in the future. I purchased the BCM Mod 3 first because I wanted a more vertical grip. I choose it because the MOE k2 looked odd with the fat bevertail and I thought it would feel odd with the hump. My hands are probably around average size to help get an idea here. Anyway I switched to the MOE k2 because the thick bevertail actually positions my hand a lot better and helps my finger rest in the correct position on the trigger with less thought to correct the overbite the BCM was causing.

Again this is just my opinion. If you have smaller hands you might like the bcm more. But even still the bevertail on the bcm is to slim. If you place your hand high up on the bevertail you crame your fingers.

Yes, the thick beavertail of the K2 (and also it's "sister" UC23 grip) is critical to hand position. The normal (non beavertail) and thin beavertail's let your hand ride up, which is fine for chicken wing shooting (where your hand will point downwards) but has NO business on a "squared" stance. A squared off shooting stance requires an almost vertical grip to keep your elbow tucked in and your wrist at a natural angle. This can only be accomplished with a THICK beavertail, to keep your (properly, now more vertical) grip angle pointing your trigger finger STRAIGHT towards the trigger. When your trigger finger has to go DOWNWARDS, your elbow will come UP, Thus it's critical to keep the grip UNDER so your trigger finger points/lands on the trigger STRAIGHT forward with elbows tucked.
The K2 got it right, and is the ONLY grip I'll put on my AR's. Kudo's to Magpul for this design (and also it's "sister" grip, Unbrella Corporation's Grip 23).
ETA: Hold you're rifle in your preferred "combat stance" with your trigger finger OFF of the rifle and pointing straight forward. If your finger is not exactly in the middle (vertically) of the trigger housing you are using the wrong grip/angle. Your trigger finger should ALWAYS naturally point straight and be able fall directly onto the trigger face with ZERO adjustment of your grip/finger angle. The K2 does this for me.

I think the K2 is my favorite grip thus far. I don't even ride my hand up into the beavertail. I grip it at the textured area. It puts my fingertip right on the trigger face. I can keep my elbows tucked in, my nose on the charging handle, and buttpad on my pectoral with the stock collapsed on the second to last notch. I find this the best way for myself to shoot in a squared up combat type stance.

Grips and stocks are a very subjective matter. They are like holsters:

What works for some, won't work for others. Folks will go through several types/brands
of holsters until they find what fits their needs. This is the same with grips.

Look at some of the grips that interest you, go on the EE, and buy 'em cheap.
Find the one that works the best for you and sell off the rest.

Just switched from a moe+ to a mod3 and I gotta say its fairly uncomfortable. The angle is great its the notch they added to fill the gap. That thing sits right on my middle finger knuckle. Maybe my hands are small? That would explain a lot let me tell you.

When I opened the mod3 the first thing that popped into my head was wow they custome fit this thing for mrgunsngears massive man hands. Then I realized I spend to much time looking at another man's hands.

I'm going to try the k2+  next 20 bucks here 20 bucks there.

Yeah that gap filler on the BCM grips are horrible.  Hurt me too.  

I cut 'em off and they're now my favorite grip.  I also foind that I have to fit the grip to het a good snug fit on every lower I've put 'em on.  PM me and I'll send you some pics of how I mod a Mod 3 grip to be a damn good grip.  

I started out with the Umbrella Corp grip, but like the K2, the thick beaver tail limits my use of the thumb safety.