I sang "Memory" pefectly once. It is the only time I ever felt a song sounding exactly the way it is supposed to sound. That was only one time, though. I sing "Someone Else's Story" from Chess more consistently well, so I might choose that. I sing "Millwork" from Working with the most feeling so I might choose that. I do the accent best on "Wouldn't It Be Loverly" from My Fair Lady. It depends on how you define best and what my mood is what I would choose. There are other things I might consider too. I care more about whether I am moving my audience than anything else, so I would go with anything where I am doing that. I tend to sing sad or angry songs better than happy ones.