Looking to upgrade from my Samsung NX300

I've owned my Samsung NX300 for almost 2 years now, and while it has served me well, I feel like it's time to upgrade to a more advanced camera/system. My budget is around $1200 (~1000 euros), including the camera body and a relatively fast zoom lens.

My top requirements are:

1) Good/sharp image quality out of the box

2) Good lens selection (including telephoto zoom lenses)

3) A good viewfinder

4) Articulating screen (touch sensitive would be a plus, but not a deal breaker)

5) Relatively compact size

6) Good battery life and/or the ability to add a battery grip

7) Relatively fast auto-focusing

I've considered buying a DSLR, like the Nikon D5500 along with the Sigma 17-50mm f2.8 lens, but honestly I would prefer to stick with a mirrorless camera instead (strictly for the portability factor).

I've also looked into some micro four thirds cameras (e.g Olympus's OM-D E-M5 II) but I fear that my image quality would suffer in the long term.

I would appreciate it if any more experienced photographers/camera owners would offer some suggestions.

Thank you.

For your budget and the things that are important to you, the Nikon is the only way to go with the new collapsible(and sharper) kit lens, and is the only one that you will actually see an upgrade, sensor wise (except the NX which has the best sensor right now,but this 24mpixel is not far behind).
I personally, after the NX300, went for the NX500 and now I am waiting the NX1, but I care a lot about video, I had a few NX lenses, and I don't see myself going the mirror way again, anytime soon, and the NX is the best croped system(in my opinion).
Your budget is kind of limited though, you won't find a very good modern body, and a fast zoom lens for 1000, maybe the Nikon way is coming close.