Economic - Because of shipping costs & distance it would be harder to buy / sell with European based firms, so there'd be less benefits to the economic single market.

Social - Because of distance and time zones it would be more costly to move, both in terms of $ (can't drive to Europe), and in terms of social costs due to huge timezone shift from friends and family.

Political - Some benefits, but also Europe's needs / wants aren't as aligned with ours. For example, due to geography it's in our best interests to maintain a good trading relationship with the Americans (which isn't ideal, but it's the reality). The Europeans aren't as incentivized to ensure we have the best trade agreement if it hurts their interests - remember that any member can block some of these treaties.

It's probably best for us to get as close as we can so long as it doesn't interfere with us negotiating our own trade ties with other nations (particularly the US). That's really the one item where it could be a net-negative.