When I think of an amazing bartender, I immediately think of Priscilla of Exclusive Cocktails. She is personable, funny, energetic, and seems to always be in a great mood. Admittedly, I always just do wine when I'm out at functions, but she always takes care of me. A bartender's personality can really make or break how much fun it is to be at a function, especially if you're there just to have an unforgettable time.
Presumably, you also have to be good at your craft. But that's primarily memorization for drinks, no? Depending on the function, there's definitely some artistry involved with utilizing speed pours appropriately, but if you're somewhere that requires exact measuring of ingredients, then it all comes down to being fast and right. This is probably more important than having personality when you're at a crowded event serving -hundreds- of people. Priscilla and her company is always on point with this. Accurate, precise and down right fun. I would use and recommend her over and over and over again.