I know this thread is rather old but I thought I'll answer you nonetheless. I own the DeathAdder Elite, Mamba Elite and Basilisk Essential. I selected the Essential over the vanilla version of the Basilisk because of the reduction in weight. For reference purposes I play with a claw grip and my hand size is 20 x 11 cm.
In my opinion the DeathAdder is better suited for a palm grip. With a claw grip I find that my ring and pinky fingers struggle to get sufficient grip on the mouse. The available area is just too small and my pinky typically starts to drag on the mouse mat., which I find uncomfortable. The DeathAdder is also the heaviest mouse among the three.
The Mamba feels similar to the DeathAdder except I can properly claw grip it. The area on the left hand side where your ring and pinky fingers rest is larger. The mouse is also lighter, which I prefer. I aim better with the Mamba. I also disable the lighting on the side bars of the Mamba because I find the one on the right sticks out below my hand when I game and it is distracting.
The Basilisk Essential is my new favorite. The feel of the mouse is quite different from the DeathAdder and Mamba and took me so time to adjust. It feels very light and once you get use to the thumb rest there is no going back. My aiming has improved dramatically with this mouse. Like the Mamba I also find it very comfortable for a claw grip. The only downsides are the small side buttons which I find harder to press than with the DeathAdder and Mamba and also the DPI clutch which I think is something of a gimmick in practice, because to ADS with your right mouse button and then to hold down the clutch while moving bamboozles my brain
Most modern shooters these days in any case allow you to set a separate sensitivity for your ADS when you zoom so I don't use the clutch. Unfortunately you cannot assign the clutch to any other function besides DPI related functions in Synapse 3.
The only mouse that comes close to the Basilisk for me is the Zowie EC2-B - similar size but different ergonomics. Before the Basilisk the Zowie was my go to mouse but I can't deny that I aim the best with the Basilisk. The advantage of the Zowie of course is that it's truly play and play - no drivers to install, you simply select your desired polling rate (125, 500 or 1000) and desired DPI (400, 800, 1600 or 3200) below the mouse with the press of two buttons. It's very convenient.