Where a Reactor Sink.Many() should have 1 consumer should use unicast or multicast

Per this question I have updated from deprecated EmitterProcessor to Sinks.Many() with the following

Many<String> sink = Sinks.many().unicast().onBackpressureBuffer();

The sink is filled with String as required and feeds back to a spring boot endpoint. Each client should have their own session via the endpoint.

Though should I be using

Many<String> sink = Sinks.many().multicast().directBestEffort();

I want to drop messages to slow consumers.