What is the best Sentinel on Steel Sentinels

A Babel is a big walker, and an Orbital is best for flying (in advanced).

A Bertha is easier to get, and owns at long range.

A custom Aquila can totally kill with speed and the Walton Mirage Device.
Some sentinels automatically have weapon slots, which can be useful.
For Example: Turtle has a heavy / ordnance mounting).

I personally prefer Orbital with its heavies and ultra gun.