I did a quick test in unfiltered, comparing throughput of both jetty and netty as underlying connection handlers. Just serving a (memory-cached) image and running a load test on that. My findings are that there is no significant difference in performance.
Apart from that, I am under the impression that both have similar scaling features aswell, like suspending connections.
Also, unfiltered is kind enough to give us very similar (if not the same) interfaces to both frameworks, so that you can't really say one is easier to use that the other.
So I wonder, why does unfiltered give us those two choices? is there any scenario when you would choose netty over jetty (or the other way around)?
My personal thoughts: I've used embedded jetty only as a servlet container. Using netty I can hanle http packages one by one, custom my own http post data storage. IMO, I think they are both sharp knifes, but netty can turn into a needle if you want to.