MacBook Pro doesn't re-connect to Wi-Fi, iPhone does
You should check System Preferences > Network and click the Advanced... button to pull up the list of saved Preferred Networks. There is an option to drag networks in a preferred order. If your home network is not at the top of the list, drag it up. If your home network is the only network in this list, select it and hit the negative button to delete it, then recreate a new Wi-Fi connection.

Sidenote: If you are using iCloud Keychain, Wi-Fi networks you have connected to on any device also using iCloud Keychain will show up on your Mac and visa versa. This can cause a proliferation of Wi-Fi networks in this list.