Coming From Nikon, Please Help Me Choose a Fuji Camera

I had a nikon D7000 and sold it about three months ago and bought me the S5 PRO and i am in love with the camera, i am sure i will keep this camera for ever. But soon i will need a more modern camera for low light and sharper images. I am being honest here, i might just buy a D7100, but i get the feeling that this camera might end up disappointing me in the end also, specially because i didn't really really like the skin tones from my previous D7000, some folks have said the new one has improved but others say the opposite, and honestly nobody is really saying anything til now, maybe because is too early and people don't know how to use the camera yet.  The AF has been said that it is pretty amazing and way better than my previous D7000, but i just don't feel like purchasing the camera only for the AF system, so i don't want to end up buying sort of like "another D7000" you know what i mean? Specially because i have been using my S5 more and more and i can definitely see the difference.

What would be THE BEST BANG FOR THE BUCK fuji camera system with a decent zoom range lens? I am informed that fuji's AF is pretty slow, so the better and faster the AF is the better for me. I don't shoot fast sports, mainly family pictures/portraits for memories that will last me for ever. But i would still like the best AF possible. Also if the camera has video capabilities would be prefferable.

I already have two prime lenses that i use on my S5, the nikon 35mm 1.8G, 50mm and 85mm, so this range is covered with the S5, so i would like to start with the best possible longest zoom lens there is from Fuji.

I am not too familiar with these fuji products, so are there third party lenses that are optional?

I would really appreciate your assistance on this.