Park4night may be better for lesser known motorhome sites and will probably give you more options (except maybe for Belgium, France and Germany). However, there is also a chance that the place is outdated. If you have found a place online, it may be the case when you arrive that you see a sign saying that you are no longer allowed to park there. So more options but less certainty. Park4night is also good for finding other amenities you might need along the way, such as finding water, parks, and dumps.