If I were you, I'd go to the store and test both devices as much as possible. We can all give you advice about the cameras, our experience with the devices, and all that, but it's still just an opinion. Ultimately you'll be the one using the phone every day and it's you that will have to make the decision.
That being said, onto the technical aspects of your debate.
Megapixels....the megapixel game is not what it used to be. Comparing last year's Galaxy s6 16MP vs iPhone 6S 12MP, both look really great, and unless you're an amateur or professional photographer, I highly doubt you'd notice the difference between the two devices of a photograph in the exact same conditions.
So far what I read about the S7's camera, it blows away the 6S camera, especially in low light. This all comes to the aperture, which mobile device cameras are slowly increasing to allow higher quality images.
Processing... The S7 will be the higher spec device because it's much newer than the Turbo 2. However, performance still comes down to optimizations and the UI. I'm sure you've heard of "Samsung lag" or "TouchWiz lag", as a user of the Note 5, I can't say I've experienced it. Originally yes on my S4 I have, especially with the Gallery app, but Samsung has since cleaned up their act and it's been smooth and quick.
Software... the S7 will launch with Marshmallow. Will there be bugs? Who knows, but if there are don't be surprised as it's the first device that will have it on Samsung's lineup. And just like any other previous versions, look for patches to fix up the little things here and there.
You mentioned you want a "rugged" phone. Unless you throw on a heavy duty case, then the s7 probably doesn't fit that criteria. The Turbo 2 is definitely the more rugged phone out of the two and you don't even need a case for that one. (There are some crazy youtube videos out there testing how much of a beating a Turbo 2 can take).
All that being said...
Go to the store and demo the two units. Try to use them as you would daily; go browse sites you frequent, try out the cameras, try out videos, and compare the two.
I have seen many change their mind about a device because of their in-store experiences. Heck, even that happened to me. I thought I was going to upgrade to the S6 from my S4, but here I have a Note 5 sitting on my desk. The Note 5 won me over with 10min spent with it in the store.
