Of course customer service and support are a given but in the end for me it comes down to performance. If the performance is good than you barely need any customer support. Therefore I believe price is not necessarily among the strongest criteria.
The problem is that the proof is in the pudding. Its very difficult to gauge the performance of a company up front. In the end you have to rely on your gut feeling as well, taking into account the overall look and feel of the company, reviews, specs as well as pricing.