As I understand from your question you were talking about type of support? I would prefer chat support, because there is enough space for both sides to correctly form questions/answers, and there's no emotional 'waves' going through the tone of voice. Often technical support requires time and patience to solve the problem, so telephone (in my opinion) isn't the right tool for solving problems, but it's a good tool for selling services or if via chat you decide to comunicate further via phone. Alternatively, I prefer ticket support system, but often these days you need to wait hours for a proper response, which is sad...