Welcome to the Community,
there might be several ways to migrate the VMs. However, what to do may depend on the size of the environment and the available supported configurations. If e.g. the "old" hosts support the new storage system, you may consider to temporarily connect them to the new storage system and the new vCenter Server to be able to use Storage vMotion (or Clod Migration) to migrate the VM's to the new storage system.
André