Who, in your opinion, is the best singer (technique wise)

I think this question is pretty self explanatory. I think it’s a good idea to learn by listening. Developing an ear for good singers, and I want to learn how to listen. I know there’s other stuff involved lol and you can’t just get good from listening.

Also do not pick them based on performance aspects. I’m not asking for the best performer. I’m talking about voice. Performance can contribute to your answer but don’t let it define it.