The ~$25/year for .co hurts a bit .. but it can also be seen as a good thing in that it keeps it more professional. What's going to happen to .xyz when all the $0.01 names drop .. .xyz and the likes are also a spammers paradise .. they are facing a huge uphill battle for long-term credibility.
I think .app will actually severely hurt .io .. while at the same time not really hurting .co much as it's broader in scope.
.web will likely take off a bit .. but it just seems a little too informal for actual businesses .. but the irony is that .web might be the ngTLD that takes the surviving ngTLD's into the mainstream.
.club I think is a good one for a couple of reasons .. but again .. does not have the broad scope of .co
I've grabbed some great .co's over the last few months .. need to start setting them up for sale .. I'm pretty much starting out now!