I know of the following, but which are the best?
IvyWise
IvyCoach
Interface
…
The list goes on. But what’s the best?
The best and most respected local advisor. One that comes recommended by someone you know and respect. These college advisors have a business in your community that depends on their reputation.
Or a well respected national advisor where you work with the principal of the firm -directly.
These aggregated marketing groups are notoriously understaffed and by recent grads or students. You have little to no ability to create a personal connection.
They always seem way overpriced as well.
I know excellent IECs who work for large firms. But you need to make a judgment about the individual human being you’re going to work with. If you meet them, and you like and trust them, then it’s silly to reject them because they’re part of a large practice. The biggest reason good people join a large practice is because they want to be a counselor, but don’t enjoy or excel at the sales & marketing portion that is essential to success as a solo practitioner. But you also shouldn’t trust anybody automatically because of who they’re affiliated with.
I give the same advice about hiring test prep assistance.
You can find lots of free advice here 
College Confidential may well be the best college consulting group. It is peer reviewed. And it’s free.
I’m always amazed that people ask this question. This is not a platform for ranking for-profit businesses.