User blog:P進大好きbot/What is the greatest ordinal notation now?

Hi. I would like to know what the greatest WELL-DEFINED ordinal notation used in googology up to now is.

There are many great ordinal notations, but some of them are not completely defined. (For them, we just have plans, directions, or dreams to define ones satisfying good desired excellent properties.)

So among ordinal notations which have already been completely defined, what is the greatest one? Is it Taranovsky's C?