If it is a good network connection, a single vCenter can do as there are not many ESX servers to manage.
Else, you can use two vCenter Servers one in each site having their own SSO installed in multi-site mode.
PRO's:
1. Speed will be better
2. This setup can scale up to add more hosts in future if there are such prospects.
3. SSO in multi-site helps have the replication of all users and groups and in case of disaster, a new SSO can be installed in multi-site mode connecting to other SO and replicate the users/groups.