I find it wholesome to be alone the greater part of the time. To be in company, even with the best, is soon wearisome and dissipating. I

love to be alone. I never found the companion that was so companionable as solitude. We are for the most part more lonely when we go
abroad among men than when we stay in our chambers. A man thinking or working is always alone, let him be where he will. Solitude is
not measured by the miles of space that intervene between a man and his fellows.

What is the best way to interpret the paradox “I never found the companion that was so companionable as solitude”?

He is asking them to consider the benefits of having companions.

He is asking them to focus on the downside of being lonely.

He is asking them to focus on the importance of close relationships.

He is asking them to consider the benefits of spending time alone.

The best way to interpret the paradox "I never found the companion that was so companionable as solitude" is that the author is emphasizing the positive aspects and benefits of spending time alone.