Solid wood vs engineered wood flooring (veneer)?

I’m currently building a house and have always wanted a real wooden floor (I’m considering walnut).

However, my builder strongly recommends using natural wood veneer / engineered woord flooring instead of solid wood. I’m struggling with this idea because I prefer something that looks and feels as natural as possible.

Has anyone here build a house or renovated and apartment and faced the same issue? What did you choose, and why? How noticeable is the difference in look and feel?

Context: we don’t have kids or pets. The house is being built in Nagano, and we will have both a pellet stove and underfloor heating. The wooden floor I have in mind is compatible with underfloor heating.