Very sorry for all the troubles.
I was researching on DSLRs till I happened to read about mirrorless cameras. I would go for mirrorless cameras if they able to fulfill my shooting (scenery, low lighting and sports) due to the lighter weight.
Nikon
- Nikon 1 V3 (2014): I was looking at this model because of more variety of lenses but I read from reviews that the controls are quite bad.
Fujifilm
- Fujifilm X100T (2014) or Fujifilm X-T1 (2014) [May be out of budget]
Olympus
- OM-D E-M10 (2014) or OM-D E-M1 (2013)
Panasonic
- Panasonic Lumix DMC-GH4 (2014) or Panasonic Lumix DMC-GH3 (2012)
Sony
- Sony Alpha a6000 (2014)
Ok. Lets looked at all the camera you have listed.
1) Nikon 1 V3 is a relatively small sensor camera (1 inch sensor size), not that it is bad, but being a small sensor, don't expect high ISO performance to match other cameras that you have listed. Also it had a 2.7x crop factor (I think), making wide angle lens, not really that wide. If you can get past that, the Nikon 1 series camera is really good and with very decent image quality. As for the controls are quite bad... it is up to you, really, some say they are bad, some say they are okay. Because different people have different needs and feels.
2) Fujifilm X100T is a fix lens camera (meaning you cannot change lens) and it has a single focal length, so you really need to hold it and play with it a while to decide if you really like it or not. X-T1 is a interchangeable lens camera though, excellent image quality, excellent lens choice, but can be pretty expensive (but with what it is offering, it is definitely worth that type of price).
3) Olympus EM10 is quite similar in term of feel and ergonomic as compared to my EM5... it is newer though. I loved my EM5, enugh say. I wouldn't say that it is the best camera out there, but it certainly did its thing well. As for the EM1, it is the professional EM series of camera, no complaint there except for the price. The image quality is definitely better as compared to both EM10 and EM5... I believe the EM1 utilize a new sensor and graphic processor as well as an update of the excellent 5 axis image stabilizer.
4) GH4 and GH3 are not exactly small in size. It is bigger than some entry level DSLR. They have excellent movie mode (the best in class) expecially for the GH4 which feature 4k movie recording. Still image quality wise... the GH3 and GH4 should be very similar or close to the Olympus EM series of camera.
5) A6000 boast to have the fastest AF around. Image quality is of very high standard, lenses available are also quite extensive.
Okay, if you are looking at Olympus OMD EM series of camera, you should also looked to the cheaper PEN series of camera, I believe by now, there is a EPL7... this camera shared the same sensor as the EM series of camera and is abit stripped down of functions... and lacking weather sealing. But is small and very portable, and image quality is excellent.
Okay. Regarding the mirrorless interchangeable lens camera as compared to DSLR, in the past, the AF system in the mirrorless camera is really not that impressive (coming from the Olympus EPL1, I can safely say that even my old Canon 1000D focus much faster), however, technology had improved and the mirrorless camera's AF matched and in some instances surpasses some of the DSLR out there. So focusing shouldn't be a problem in both good and not that good lighting.
Most of the mirroless out there offered pretty extensive lens library so you shouldn't worry about lacking of lenses. But to be sure, before you launch into buying a camera, do some research on the availability of accessories and lenses.
And although many people would tell you that mirrorless camera are small... and small is good. But from experiences, small is not necessary good. Why? you need to take care of ergonomic. Some people - like myself, have big hands. Holding a small camera with no grip or insufficiently deep grip for sometime will make your finger ache. It was so bad even for my EM5 that I need to buy a third party optional grip for the camera to fully enjoy the camera... the orginal one is expensive at that time... so do factor in that in your purchase.
So to make things simple, check the following before buying anything, you can safely strike off the image quality department - all of them are good,
1) Ergonomic - go down to the shop, go to megastore - some of them have dummies out there for you to hold, and feel the camera see if you like the feels.
2) Menu - check to see if the menu and button layout make any sense to you.
3) Lens and accessories availability - check to see if the camera you liked offer those lenses that you need for your work... for example - you might want ultrawide angle lenses for landscape and architecture photography, dedicated macro lenses for macro (of course you can purchase addon), telephoto lenses for sports and wildlife, etc etc.
4) Others - this is tricky, you need to list down a list of the wants and needs... and no one can tell you what you need and what you want. Yes, we know you want to shoot scenery, low lighting and sports, but what about weather sealing, what about about to stitch photos in camera, etc, etc.
Hope this help.