Support =/= technical team.
An exchange could have an extravagant design, and the fastest trade engines in the industry, but if it doesn't have a good customer support on which customers are able to depend on, then it's literally good for nothing at all.
That would be my main criteria if I were to choose an exchange, as well. The level of responsiveness from the support team is extremely important. If they are active on social media and answering queries there, then that's bonus points. I would rather use an exchange with a decent support team with small trading volume, than a big exchange with terrible support.
Of course, technical support is a very important factor because it will be the first step to communicating for all kinds of problems and support. For that reason, we have to make a choice by taking this factor into account so that when we have any problems, we will get an easy, fast and quality service.