The top shaman
"solo artist" is a barbarian. Troll race is also up there too. These players got to the top of the list not due to the race they chose but due to their skill. You seem to be approaching the game wrong when you say there is a "best" race. When in fact any shaman race can do anything because the class itself is so powerful.
Again, play what you think is fun. You will be looking at this toon for a long time if you want to get to 60, so don't choose a race just because people tell you it's the best.
You need to pick a race and
make it the best.