the difference between "most of all" and "best of all"

Best of all, I can sing Korean Pop songs with my friends.
Most of all, I can sing Korean Pop songs with my friends.

What is mainly different in meaning?

After the phrase of "best of all", is good thing followed?

[RonBee]

That which is best of all is better than all the rest. I am not sure how you should use "most of all" (if it should be used at all).

~R