Which method or component is best to regulate 42 to 3.3 V?

I quite like the LT8631 (1 amp at 3.3 volts and input voltage range up to 70 volts): -

Or maybe the LT8630: -

Or possibly the LTC7138: -

Or choose your own buck converter using the Analog Device's selection tool.

A buck converter is the best approach

A linear regulator circuit in the worst case is going to have to drop 42V down to 3.6V = 38.4V. At 160mA the power dissipated by the regulator will be 6.14W.

On the other hand a buck convertor will drop voltage to the required level with possibly 90% efficiency (less energy wasted as heat) and likely reduce the current consumption to 3.6/42*160mA = 13.7mA allowing your battery to power the circuit 11.67 times as long.

https://www.monolithicpower.com/en/products/dc-dc-power-conversion/switching-regulators/step-down-buck/converters/vin-max-48v/mp2492.html or similar could do this.

The best method is to use a buck-topology switching regulator.

For example, Analog Devices LT3437 has an reference circuit/example for your application