At U10 I would go with the team where your son will enjoy practices and games the most. At that age it should be about fun.
In general the bigger club will be more consistent in that they will have enough players to field teams with similar skilled players. They will have the infrastructure to run the team. Small clubs and teams can be great, but they can also fall apart because not enough players one year, or be very dependent on a single coach who leaves and takes half the team with them. At bigger clubs, being there from young ages is an advantage for making teams later on. There will always be things you don't like about a coach's strategy or roster decisions or playing time or whatever. If you son is learning and having fun that's most of what matters.