Flat pedals are good because you can just jump on and ride.
Cleats are good because they encourage better pedalling technique. And encourage the use of stiffer soled shoes for better power transfer and less fatigue of the feet on longer rides. Cleats are bad because those shoes tend to be expensive. And for winter, overshoes or different shoes (/boots) are needed. So that's either more expense or more faff.
I think the gains from using cleats are marginal. Probably more gained from the shoes, over say trainers.
I think it is going to come down to how you ride, and how much electrical assistance you ride with. If you are aiming to conserve battery life for longer rides, then it makes sense to make the rider as efficient as possible. If you are looking for convenience over any efficiency gains, then flats are probably the way to go.