"Best" doesn't always mean "easiest."
A man with a 6 inch penis might be "easier" to give head to, it's "easier" to get the whole thing in etc.
But, I like a challenge. I also like the feeling of the head on the back of my throat, so for me, "best" is bigger. It's not always the "easiest" but it's what I learned on, and what I'm used to. But, it's still often a challenge, you have to approach a well endowed man with care.