A good word for the opposite of pretentious?

Solution 1:

Will unpretentious work?

Not attempting to impress others with an appearance of greater importance, talent, or culture than is actually possessed: a friendly and unpretentious hotel

in spite of his fame he was thoroughly unpretentious

1.1(Of a place) pleasantly simple and functional; modest.

(Oxford Dictionaries Online)

Solution 2:

down-to-earth, defined by Merriam-Webster

informal and easy to talk to

practical and sensible

unpretentious -- Example: surprised to find the movie star so down–to–earth

Solution 3:

Genuine (M-W) is mentioned by the OP, but there is an alternate definition which makes it more appropriate than other dismissed terms:

free from hypocrisy or pretense

Solution 4:

unaffected (dictionary.com) -

1. free from affectation; sincere; genuine:

The man showed unaffected grief at the death of his former opponent.

2. unpretentious, as a personality or literary style.

Solution 5:

Modest — M-W

Unassuming in the estimation of one’s abilities or achievements

"Despite the magnitude of her work, I find Kate surprisingly down to earth and genuinely modest about the achievements she will leave behind when she hands over the reins on her 65th birthday."