When you are looking to outsource anything, not just software development or maintenance, anything at all, you are not looking to get the best technology solution. That is a given. That is by default. That is a requirement. Without that there is no outsourcing happening.
What you are looking beyond that is a solid team that shares your passion and zeal. Someone who can stand right next to you in turbulent times. A bunch of people who share your vision, are willing to work towards fulfilling your vision. You are looking for someone who can help you look good in front of your customers, management etc.