XHP70.2 6V Buck driver and mosfets advice?

I am currently in the research and development phase of building my own quad XHP70.2 (6V) flashlight. I will be running it of 2S 18650 but would like it to be 3S or 12V capable.

I plan to build an I2C controllable LED driver so I can reuse the driver in a single LED flashlight in the future. The driver board will be controlled by an ATtiny85 for temp and current sensing. I plan to use a voltage controlled PWM modulator at 1Mhz for the Buck driver.

I intend to run the LED’s at between 8a and 12a continuous depending on the cooling capability.

Which is the better buck driver:

NCP3420 : https://www.onsemi.com/pub/Collateral/NCP3420-D.PDF
OR
TPS28226 : http://www.ti.com/lit/ds/symlink/tps28226.pdf

They both seem like similarly adequate drivers but I am aiming for max efficiency.

Also, I am planning using SiR800ADP Mosfets https://www.vishay.com/docs/79335/sir800adp.pdf
are these suitable/capable and is there a better option?

Thanks in advance for any responses.