I think vert.x looks pretty cool and was just about to try it out before this. I'm doing some work that requires a neat Java based NIO web server. I've done a lot of work on top of Netty directly but vert.x looks like a nice higher level abstraction (e.g. routing etc.).
nodejs is great but having the JVM and it's vast set of libraries is pretty compelling.
That may well be the case. I haven't benchmarked regular IO vs. NIO recently. Certainly when I did before, there wasn't too much in it but I did get more reliable latency from NIO and the rest of the stack is non-blocking so it's a neat fit.
In theory NIO scales better than regular IO for the 100,000 connections case but that's not one that I need in my particular scenario.
nodejs is great but having the JVM and it's vast set of libraries is pretty compelling.