white leather is very sporty and white fabric is more formal I think, unless you are doing white fabric slipcovers; so what feel do you want and then go from there.....lots to consider.

"Acceptable"? How is that even a thing?

I don't know where you live, so can't guess the weather, but here in the mid-Atlantic states in the winter time, I dislike leather furniture. I don't care if the house is 72 degrees, leather feels cold (especially on my shaved head). I have resorted to throwing a scarf over the back of my easy chair to keep my head from landing on the cold leather. Looks like my grandmother's antimacassers (except not lacy).

I like the look of leather, but I don't like to interact with it in certain seasons.

I agree, Patricia, that leather warms up to body temperature, but those first few seconds are a shock to my bare head!

This is my cream leather sofa and the style of the piece really determines whether it is formal or not.

My dog spends a lot of time on the sofa, but usually kicks off the light pillow and then sleeps on the red one. So maybe it is cold :>) I have had it for a year and have never sat on it. I prefer the chair.

Of the two photos you posted, I prefer the beige fabric sectional. It is more streamlined and will work in a variety of different rooms. I am not a fan of the puffy arms and headrests of the first one. Not sure if that is a component of modern contemporary, but I would try to avoid it. Ted is right. Pick the sofa style you like first. Worry about fabric second.

Modern/contemporary design is often accused of giving a room a "cold" feeling. One way to counter the coldness of the modern design is to use fabrics and textures, so I would vote for using fabric and not leather in this case.