There are two issues here: focus and quality.

You want a consultant who focuses on the sort of issues that interest you. If integration with existing enterprise technology is a key concern, you should consider someone with a lot of industry experience. Or, you might want something state-of-the-art, in which case you should get someone fresh out of academia who is up with the latest techniques.

The get someone who is very good at this focus, I think referrals and recommendations are the best route. This is true for almost all hiring.

There are two issues here: focus the speciality of the consultant, and quality.that the consultant is good.

You want a consultant who focuses on the sort of issues that interest you. If integration with existing enterprise technology is a key concern, you should consider someone with a lot of industry experience. Or, you might want something state-of-the-art, in which case you should get someone fresh out of academia who is up with the latest techniques.

The To get someone who is very good at this focus, I think referrals and recommendations are the best route. This is true for almost all hiring.