Fast, easy serialization library for Unity?

I'm looking for a serialization library that meets those requirement to save/load seamless loading zones in my open-game-world.

• good serialization performance, ideally as fast as protobuf-net.

• less annotation use than protobuf

• can serialize/deserialize full object graph/reference. (but no need to serialize gameObject/monobehaviour).

Some of my options are protobuf-net, MessagePack, StackService.Text, DataContractSerializer, Json-NET, NetSerializer

I'm testing protobuf-net v2(without annotation) right now. But if you have used one of those libraries or know other good library, please tell me if they meet the requirement or not.

Thanks