The first step to choosing a chain is to read the printing on the bar. It will specify things like pitch, typically .325 or 3/8. It will also specify gauge which is often .050 or .058. Also listed will be the drive link count which for my 20 inch bar is 72dl.
Best chain begs the question of what kind of cutting you are doing. If you are working with dirty wood a semi-chisel lasts longer than a chisel but in clean wood a chisel is faster cutting. If you return and post your cutting needs/uses along with the information from the bar there are folks here than can definitely give you some good advice.
I am running a 3/8, .050, 72dl on my Husky in full chisel, but all of my cutting is in clean wood and I don't hesitate to touch up the chain every few tanks of fuel to keep it razor sharp.