What is the difference between OpaqueTridentKafkaSpout and TransactionalTridentKafkaSpout? When would you use one over the other?
It is not about which one is better, it is about your requirements.
Storm trident topologies deal with batches of tuples.
Transactional storm spout guarantees that batches are non-overlapping and that the same batch will always contains the same set of tuples. Opaque storm spout guarantees that batches are non-overlapping, but the contents of a batch may change.Which to use use is up to your system requirements and semantics.