Symmetric protocols for consensus
This paper [1] provides a consensus algorithm in a model where, in each round, each node can query 2 randomly chosen nodes and update its own value accordingly. As this is essentially a balls-into-bins scenario, the load balancing will be very good. It is shown that this "converges" to a consensus within $O(\log n)$ rounds even if an omniscient adversary corrupts up to $O(\sqrt{n})$ values of the nodes in each round. 

I would say the main reason why many protocols have a leader is for having a coordinator that orchestrates the progress of the protocol. Note that most classic work on consensus focuses on achieving the best possible fault-tolerance, whereas load balancing as not always a primary concern.

[1] Benjamin Doerr, Leslie Ann Goldberg, Lorenz Minder, Thomas Sauerwald, Christian Scheideler: Stabilizing consensus with the power of two choices. SPAA 2011: 149-158
http://www.cs.ox.ac.uk/people/leslieann.goldberg/papers/SelfStabilizing.pdf