I am going to install a hds live 9 on bow, what is the best mount?

what type do you want?

comfortroll has an over the pedal type priced right, you have to drill the holes for your gimbal is all.

https://comfortroll.com/shop/ols/products/on-deck

for pedestal I got one of these. well built and was perfect for seeing back graph over the other graph.

https://www.basspro.com/shop/en/bass-pro-shops-lockdown-marine-electronics-mount

I've installed 2 of the Balzout Mounts. They're not cheap. But they do hold.
For the price of the mount, I am disappointed in the low quality hardware they provide for the install. But other than that, I've been pleased.

Precision Sonar makes all kinds of mounts and plates for most boat mfg

Check out Boat Logix. They have the Universal Mount and the bow mounts... Quality products... Dan

https://boatlogix.net/product-category/bow-mount/

https://boatlogix.net/product-category/universal-mount/