Decent management. A lack of change of business model, no rug pulls and such. Fair value for money. Consistency over the longer term. No lock in or other forced relationships. Large enough to be useful and to have decent team size, small enough to not have the illusion they'll conquer the world. Healthy competition.
Are there any companies existing you would trust?
I honestly can’t name a single one I know of who could pass that criteria
Edit:found your other comment answering a similar question
Admirable, but short of a local credit union I used to use (which I am no longer with as they f'd up a rather critical transaction), I can scarcely imagine a business that fits such a model these days. The amount of transparency needed to vet this would be interesting to find though, and its mere presence probably a green flag.