If the cylinder is located far away from the tap, and the boiler is close to the tap, and that particular tap is used often, then the combi outlet is better as the hot water will arrive at the tap much quicker and the amount of hot water left in the pipes will be small.
For that it makes very little difference, because unlike turning a hot tap on briefly many times a day, the cylinder will be heated only once or a few times for an extended period, and the amount of hot water left in the pipes is insignificant compared to the total energy put into the cylinder.
Cylinder location relative to the hot water outlets is far more significant, and all of the pipework should be properly insulated in all cases.
Just jumping on this, what is the best way to get the pipes from the first floor down the walls to the taps on a block construction house but have room for them to be insulated and not touching concrete or board adhesive? Plastic fittings are also large.