Objective-C is a decent language and if you want to stick to the Apple universe then you get a rich set of frameworks to work with. And to be honest, many of these frameworks are really excellent.
But—and this is why I left Objective-C behind—you are really tied to two platforms, namely OSX and IOS. While these platforms are good for client applications, there is not much server related stuff in the Apple universe. Apple focuses on technologies to create consumers of their devices and services. That's ok, this ears their money.
To be honest, for me the really interesting stuff is 'big data', 'databases', 'functional programming' and 'concurrency'. I always liked the big iron stuff and the bleeding edge of technology in the big iron stuff. And that’s the place where Apple decided not to go …
So while I stay on the Mac OS X platform, my preferred language at the moment is
Clojure
. It’s a LISP based language that has access to all the java libs out there. And while you may sniff at java on the desktop, it's still the most widely used language with lot's of stuff related to third party libs.
If you want to learn something about clojure, have a look at
this
video presentation. It's from the inventor of clojure.
Combined with modern IDEs that focus on instant feedback like
Light Table
(early alpha at the moment), this results in an really new experience which I regard as much more advanced and fun than any Objective-C coding I did before.