Welcome to the forum. I think it does not matter, so maybe charging to 100% is the best option. In my particular case I do it to 95% because my first 2 miles every morning is a smooth, though noticeable, downslope drive. If the battery is at 100% the car won't be able to use regen brake, so it will trigger the combustion engine everytime I release the throttle to avoid speeding.
Enjoy your new Kuga!
(P.S. please edit your profile to add your vehicle's details to your signature, so you won't need to repeat them once and again )

 

@Slumberman why not introduce yourself in the new members and pop your Kuga details into your signature as requested by your welcome email👍

 

It seems strange to me that if car manufacturers really believed it is a bad idea to charge to 100% then why allow it? Surely they could prevent it in the software. Personally I always charge to max

 

Most manufacturers guarantee the batteries for 8 years or so, so it shouldn't be a major concern tbh. My last car, a Cupra Formentor PHEV stated in the manual that if charged to 100% then the car should be driven as soon as possible i.e. not left stood for many hours/days whilst at 100% charge. Having said that, the guarantee remains, how could they prove how it's been charged etc.
I have read that the HV batteries get stressed if left at 100% or 0% for long periods. Many mobile phone/tablet manufacturers say the same and many have an option to only charge to 80% "to protect the battery". I've always charged my phone to 100% overnight, every night, and never had an issue.
My PHEV's, past & present, have sometimes been left for several days unused, so I do set the option to charge up to 80/90% and then top up to 100% a few hours before travelling, but that's just my preference (I do have a dedicated home charging point so it's much easier to control than the Ford Pass app). One big advantage though is that if its plugged in just before a journey, the car can be conditioned i.e. heated or cooled without using the car's power.

 

Also when 0 miles is shown the battery isn't at 0%,some 15% or so is kept back for normal driving. Hence why a full charge is only about 11.5 kwh when battery is 14.4kw.

 

Obviously on a much smaller scale, but in the model aircraft world with lithium-based battery powered models the advice is to charge to about 80-85% if the battery is not going to be used for a while. This is to optimise the battery's longevity. It's said that the battery should only be charged to 100% if it's going to be used very soon.