I would suggest looking at experience with projects similar to yours. This is often a key factor, especially if they already have some experience in architecture. And it is also important to discuss all the details right away so that there are no misunderstandings at the final delivery stage

We ourselves have recently been looking for an architecture rendering company, and it is a real challenge. The main thing is to choose those who understand the specifics of architecture and can offer something more than just a pretty picture. It is important that they are able to convey the idea and vision of the project. I can advise you to look here - https://render-vision.com/, they specialize in such things and do it very well.