Swift 100%, obviously ;). It’s a much more modern language that is easier to learn, which goes a long way in bringing new developers onto a project.
There is no way to measure how good a programming language is, and there's not even an universal agreement on which features are desirable and which are not.
Optional as an example: For me personally, the concept is one major reason to like Swift more than Objective-C, but others (probably not here ;-) really like nil-messaging...
I guess the least controversial argument is that the syntax for blocks in Objective-C isn't as nice as in Swift.
Oh men, for work i code in RPGLE. Trust me, swift is way better!
The only thing i found a little difficult is work with dates and time
I loved Obj-C while everyone I knew hated it, for 10 years. Then I tried Swift and cannot look at Obj-C anymore. In short, Swift is way more expressive. You will probably need both, but Swift is better. Amen
I don't think we need to have this kind of discussion here.