The "ideal" thermostat is an on-going debate. Here is my *OPINION* on the question.
1. Ideally you want to get a thermostat AND a cooling system that allow your car to run at the same temperature all the time. (Not quite possible in real life - but get as close as you can.)
2. Realize that the thermostat just determines when your radiator starts trying to cool the engine via the coolant. The thermostat temperature is not *necessarily* the temperature your engine will run at (or even close to).
3. Getting a thermostat that is just a few degrees below the "steady state" temperature your cooling system can maintain is optimally so that your engine operates at the same temperature nearly all of the time. This means the wear patterns and stresses are stable and the tolerances within your engine will be both much tighter and will last longer.
For my car I run a 180 thermo, my cooling system keeps it between 180 and 185 almost all of the time - even in 100+ degree bumper to bumper "rush hour" driving conditions. So that works for me. Your engine and your cooling system may work better at 196 (the temperature Ford choose originally). A 160 is simply to cold for the engine to function properly, the wear will be accelerated at that temperature (at least that is what the websites which report engine wear and tear research claim). Or, alternatively, the thermostat will open at 160 and engine may operate there for a while, and then when the load increases the engine will fight its way up to a higher steady state temperature, thus causing more wear as there will be a much broader temperature range over which the engine actually operates.
In the end its your decision, attempt to get informed, and then decide what your priorities for the engine are.
John Harvey