"We choose our partners by..."

We choose our partners with discernment

We choose our partners discernedly

Discernment is a term used to describe the activity of determining the value and quality of a certain subject or event. Typically, it is used to describe the activity of going past the mere perception of something, to making detailed judgments about that thing. As a virtue, a discerning individual is considered to possess wisdom, and be of good judgement; especially so with regard to subject matter often overlooked by others.

Consider simply saying:

We choose our partners by ourselves.

We choose our partners on merit.