With very few exceptins, if you notice the vibrato, there's too much of it. As others have said, don't try to develop it. And listen to yourself, and learn to recognise it and keep it in check.

Of the people in that list I've heard of and enjoy (not too mnay), most generally limit their vibrato.

One exception to that rule, a singer who has quite a noticeable vibrato and still sounds bloody marvellous, is Martin Wyndham-Reed. There's an exception to every rule.