obsigna, last time I tried to get Étoilé to work it failed - do you know the current status? I really like the concept, but if it failes to work and only takes time...
I have to admit that a few years passed by since I stopped my GUI efforts on FreeBSD. That time I installed GNUstep + Étoilé directly from the source, without the ports, and I used GCC for compiling everything. It well might be, that the switch to clang and another Objective-C-RTE broke some things. I can only tell, that my experience with GNUstep on FreeBSD was that promising, that I would try hard on fixing things before even considering another framework (than GNUstep+Étoilé/Cocotron/Cocoa) for GUI development.
Other than that, I would like to see more about swift before I form a final opinion - if such a thing exists. Opening it up like apple did is a good idea, and as long as they keep the commit gate, the language and tools should be usable and not drift into Linux-only land.
Perhaps, you mean something different with
"... I would like to see more about swift before I form a final opinion ..." – anyway, have a look at the book published by Apple –
The Swift Programming Language (ePUB - 734 pages). This book would tell you everything you always wanted to know about
Swift, but were afraid to ask

Seriously, you need to search hard to find an equally well written description+reference of another language, and at the same time it comes with a free license, i.e. CC BY 4.0.
If GNUstep really picks up (as promised by the chief maintainer Gregory Casamento – at least he created already a fork of Swift on GitHub), then we may see Swift as the replacement of Java in some future. Swift would produce way much faster applications, since it is a really compiled language (like Objective-C) and the code runs almost on the bare metal, utilizing only a tiny RTE for dynamically dispatching of objects.
For the time being, I comfortably stay with Objective-C.
PS: For those, who want to play with the language, IBM set up a Swift Sandbox, and you are able to work through the tutorial in the Swift-Book just using a browser, without needing Xcode on a Mac.
http://swiftlang.ng.bluemix.net/