canon - 6D or 80D for upgrade from 100D?

I am about to buy a new camera. I stepping up from a Canon 100D. I mainly focusing on portrait, fashion and street photography. 100D done well so far as a hobbyist but I really feel the need to step up from it to be more serious about it and I feel the limitations.

I planned to buy a 80D in July but now that 6D Mark II coming 6D will be $550. So we will have a full frame camera cheaper than cropped 80D.

On the other hand it seems to me 80D is a much better camera. 6D's only advantage is being full frame and its low light capabilities and now the price.

So if 6D will be really $550 is it worth that price? Is there lens worth $500 (the difference between the two Camera) that is very good for portrait and makes 6D worth it instead of 80D?

Answer

So first let's get this nonsense about a $550 full frame 6D out of the way.

The article at the end actually says (with the full context required to understand it properly) :

if you love a cheap camera and have no desire to lean into the micro four third ecosystem than something like the new SL2 could be right up your alley. As with the Canon 6D, it goes on sale in late July of this year. Yet the body alone will retail for just $550.

The new SL2 (a 100D mark II) will go on sale at about the same time as the 6D mark II and it is the SL2 that is expected to retail at $550

So no, the 6D is not going on sale at $550.

I am about to buy a new camera.

But you don't say why !

I stepping up from a Canon 100D.

In what way "up" ?

About the only certainty is that you'll be stepping up is size and weight.

But the 100D is a very good DSLR.

I mainly focusing on portrait, fashion and street photography.

Nothing there that needs full frame, or even something other than a 100D.

100D done well so far as a hobbyist but I really feel the need to step up from it to be more serious about it and I feel the limitations.

What limitations ?

This sounds more like the belief that somehow you need a more expensive camera to get better photos. You actually need more skill usually. Lighting and composition first, everything else after.

6D's only advantage is being full frame and its low light capabilities and now the price.

Well not the price (explained above).

You don't appear to need better low light capabilities for your primary interests.

Have you flash experience and lighting experience ? These are the areas to concentrate on for fashion and portrait.

The small size of the 100D makes it a good choice for street work, IMO.