The lack of a f2.8 17-50mm lens is really getting on my nerves truth be told, there's the Zeiss 16-70 f4 but that's more expensive than a Canon 17-55mm f2.8 IS!
I have the 18-105mm f4 and the distortion is hilarious, easily correctable but even at f8 the corners aren't sharp. It's okay for video but total trash for pictures IMO.
I think it's best to stick to primes for this system. Both for size and cost, I get good results with the Sony 35mm f1.8 which is the only thing stopping me from selling up.
As for the a6300, another £100 and thats A7II money, just makes no sense at all really. Unless you want 4k video of course..