It's remarkably hard to find any recent discussions if libressl is ready for production. A comparison on https://en.wikipedia.org/wiki/LibreSSL seems to indicate libressl is less vulnerable.
/ sw_vers
ProductName: Mac OS X
ProductVersion: 10.11
BuildVersion: 15A282a
/ /usr/bin/ssh -V
OpenSSH_6.9p1, LibreSSL 2.1.7
So given that we live in a world of imperfect code, it's a question of what's least-bad. OpenSSL is known to be a horrific mess of crufty under-maintained code, which is a big part of why it keeps having major security breaches. Like this article points out - nobody has bothered to compile this option for more than a decade. Options lead to internal complexity which leads to crap code that nobody can/will maintain, which is the wrong path for security-critical software. If nobody uses it then get rid of it - if someone wants it they can dig it out of revision history.
The OpenBSD folks are happy enough with LibreSSL that they released it with OpenBSD 5.6, which is good enough for me. I'm sure there's some esoteric vulnerabilities lurking and maybe the cleanup introduced a few new ones, that's just the nature of non-trivial software. But in the big picture I just can't see it as being any more vulnerable than OpenSSL, and that seems to have been borne out in their respective track records recently.
See, for example, shellshock, which was in a piece of software that's been battletested by most people who use a command-line for the past, oh, twenty years or so.
Whether or not the developers actually know what they're doing with respect to writing secure software in the language of the project and are sufficiently OCD in their process to catch most mistakes before they reach production is very, very much more important than "battle tested for X number of years".
I started testing nginx compiled against LibreSSL from before portable was official[0].
If your goal is security, as far as I'm concerned it's met that goal since day one. If the goal is stability, the slimmer codebase is certainly no less stable than OpenSSL.
There were however, several occasions places where code didn't compile for various reasons. Some were fixed by nginx, and some were fixed with PRs I sent LibreSSL. Key to this is that there were situations where newer releases of LibreSSL broke my build process.
If you were on a project less ubiquitous than nginx, you may find that sort of hacking a waste of time.
If you have the resources to use it, it's posts like this that strongly turn me in the direction of LibreSSL.