This question is definitely opinion-based. As a general rule, any time you say 'what (piece of software or hardware) SHOULD I use for (x task)?' you're going to have a WIDE variety of responses.
For example, some people are going to tell you it's better to partition drives with Gparted, while others may tell you to buy and upgrade some off the wall shareware you've never heard of before, while yet others may tell you it's best to just do it all manually from the command line.
I tend to always use the latest stable version (and occasionally, beta) of EVERYTHING, so if you ask me personally, I'm going to tell you that the latest is almost always best. But for certain niches of application, the latest may have bugs that haven't been worked out yet, or may have removed support for some functionality or software that you would consider essential to your own Linux use.
Therefore, the 'answer' here is that there IS no answer that applies to everyone. My best advice is trial and error. Read the release notes, know the differences, load them up, update your GRUB, and try them all out one by one. If 3.13 works better for you, then use it. If 4.2 works better, use it. This level of freedom is one of the major reasons Linux has been so successful.
It's up to you.