Frank Carroll seems like he's really tough on his students, but he manages to be tough and also garner their lifelong trust and respect. Also, would you want anyone else in your corner? He fiercely supports and defends his students when they're skating up to his expectations.
I have also been so impressed by Yuka and Jason, because they seem to take a holistic approach to skating rather than focusing in on just what needs to be fixed that day. They especially seem like a great team for older skaters, since they encourage their students to take ownership of their own skating.
Mostly, I like when coaches have clear expectations, respect their students (and are respected in return), and allow their skaters to take the spotlight. With these coaches, you always get the sense that the skater's health and readiness is their absolute top priority.