Better and best are derivatives of "GOOD."
An interesting way to think of "better" is as a combination of "GOOD + ER,"
and "best" as a combination of "GOOD + EST."
Good: (For more info, check out the "GOOD"
page.)
better:
The sign for better comes out to the right a bit.
BEST:
Notice that the sign for BEST makes a much bigger movement. It actually
dips down a bit for emphasis prior to moving "way up." The more you
exaggerate this sign, the more your are emphasizing how much better
something is than the others.