"Best" will depend on what it comes with, and your cutting conditions and ability.
It will probably be a 3/8ths low profile or a .325.
Many of the 3/8ths LP chains are very fast even though they don't come in a full chisel square grind.
Some of the "safety" chains cut remarkably well now days too.
Most of the semi chisel chains are somewhat slower than full chisel but you might need a stopwatch to really tell the difference.
My advice would be to run what comes with it for a while. Learn how to sharpen a chain really well and go cut with people who have more experience.
You can learn by watching them and what they use.
Bars, chains, rim sprockets, file guides and the like can run into a lot of $$$ quick.
No need to spend a lot of money to find out something doesn't work well for you if you can run someone elses saw, or use their sharpening guide to learn the same thing.
You will be wanting a bigger saw before Valentines day any way so no use in dumping a lot of $$$ in this one all at one time.
Mike
