Thanks to you who has jumped on to my post so soon? After reading your responses, I Too am thinking of the 6D, its not imperative I have 5 DIII, but I do like its full function.
I'm no longer shooting the things i used too, today its for entertainment, not dead serious. I still shoot for our local zoo, I volunteer my time and photos, no charge to zoo. Lately I've been using my D7100 instead of my D2X or D700 its lighter, and using my 80 400 VR. As a lightweight kit, due to past health issues, I'm using my D3300 as my day to day kit, its a fine little kit.
If you should check my past profiles health is a serious issue, just now getting to where i can walk more than a short distance. I had wanted the Nikon D600 when it appeared? but then the roof caved in, and with all its issues i wanted no part of the D6XX series.
My D700 is a fine camera and heavy, add my grip for the 8 fps rate and its a beast!, I just never warmed up to it. It still after 5 years has less than 20K "clicks"
A lot of your descriptions are more the way i shoot today, more so than years ago, I don't need a high frame rate 5 or 6 is fine, buffer not on top of my list, I shoot RAW, and use LR6, center focus point works for me most times and not fast action like BIF, gave up on that,I shoot song birds in my blind in back yard.
The 17 40 to buy from a friend is just fine for me, she used it on her 60D, for several years, but she just never liked it, now even less.
So information of the 6D, is more to my liking I just never read much, I just kept reading about 5D series.
I'm just a "plinker" anymore, just simple shooting,and out walking, as my health will allow, but I don't want to give up the DSLR, thanks I'll spend more time looking into the 6D, price more to my liking too.
The lens system if I can manage it would be 17 40 and 70 300 L lens[ Jennifer has one] and down the road, I'd like to spring for the 50 1.2? I've looked at that lens, another friend shoots a 5DMKIII and only the 50 1.2. So I do find your help helpful, but I must come to grips to sell some equipment I've had for many years my 300 F4 AD is at least 20 plus years[my bird blind lens] I'm a keeper, hard to part with older equipment still shoot my D200 on pretty days, but I have too much equipment and must adjust.
I post to flickr, no printing, my site is palmerb16, I'm having almost as much fun at 70 as i did back in the 80's.
"dog house riley'
I've owned the 5D Mark iii and 6D. I'd get the 6D. As far as the 50 1.2, I'd avoid that. Some may tell you other wise but it's just not worth he money. It cost a ton of money and when you see it compared to the 50mm that's like 100 dollars it doesn't wow you. You don't want to spend that kind of money and feel like, "It's just kinda better than the plastic one." You want to invest in something that is a LOT better. Hopefully Canon will update that lens to something much better.
The 24-70 2.8 ii, while an expensive lens, only goes 2.8, won't do the 1.2, but honestly the 50mm on that looks sharper to me. In fact that 24-70 2.8 ii seems to be sharper than most primes I've owned.
I own Canons sharpest prime lens and I've compared it side by side with my 24-70 2.8 ii and honestly I can't tell the difference. If there is a difference, it's subtle at that point because once it reaches a certain level of sharpness, even if another lens is sharper, you start to not care or even be able to really see it.
I also owned one of the highest rated primes out there from Zeiss, is it sharper than my 24-70 2.8 ii? Probably but it's not the night and day you'd think it is.
There are some lenses in which the sharpness does start to matter. People will hate me when I say this, but the 24-105 F/4, that lens is horrible. It may be versatile in focal length but the thing is soft and not just the edges, even the center is soft. I don't mind F/4, I mind the softness.
If you need lenses that do 1.2 it does get complicated because a lot of times we are paying a ton of money for 1.2 but once we use it for anything above 2.8 it starts to become no different than things that cost more than less the price.
Personally, on a full frame camera, I don't really need anything beyond 2.8. I understand some people do and like the look of the extreme shallow depth of field but to me 1.2 gets to the point where I don't like that look on a full frame.
The only time I go to F/2 or F/ 1.8 even is when there is no choice. Also in the days where I did a lot of video, sometimes I would like it for shots.
When it comes to portraits, even 2.8 doesn't feel needed to me anymore. I have a 135mm F/2, at 2.8 the background is completely gone but it can start to affect the subject. I have the 100mm F/2 as well, same thing.
This is why I tried to like the 24-105 F/4. At portrait distances, F/4 on a full frame camera is plenty enough. But the sharpness level just wasn't there, especially on my copy.
With Canon, things are kinda weird right now. The stuff I do professional is Landscape. As a Landscape shooter I want the best possible lens I can get at my preferred focal lengths which are mostly 24, 28, and 35. I used to do 16mm but I don't like that look much. I looked into getting the 24 and 35mm primes and when I did the test, it was quite clear the the 24-70 2.8 ii was better than both of them and not just a little bit.
The new 35mm they are either coming out with or will come up with, (only heard about it, have not seen it.) I don't know about.