In terms of functionality, I do not think either has advantage over the other. However there could be reasons why one would prefer one IGP over the other:
1. Provider network environment - do all you equipment support the IGP? Vendor support for the IGP in relation to MPLS TE and other technologies you want to support.
2. Availability of technical expertise for the IGP
3. Ease of deployment and scaling. ISIS is easier to deploy and scale on IPv4/IPv6 dual stack environment compared to OSPF which requires separate processes and area design.
It's a matter of organization choice in my opinion