The dark ottoman fits better, the white bench is an amazing piece of furniture but it is not ment to be a replacement for a ceffetable. It is a side bench.

Try two small ottomans and a table to pull them out from underneith.

The color white is fine because it matches the wall. All you need is a pattern carpet in your white, brown and green that fits under the entire seating area.

you need a rug

The bench is fine, nice proportion for the seating plus it adds comfort. But all you have are solid fields of color, the sectional, the floor, the walls, the bench. The right pattern in a rug would tie all the elements together.