What is the best grade of hardwood lumber?

These are the lumber grades in the US:

General construction lumber:

Lowest

Utility (Not usually available to the public)

3 (Not usually available to the public)

2, Stud, or Standard (Lowest common grade)

2+ or “2 or better”

1 or Premium

1+ or “1 or better” (Highest common grade)

SS or Structural Select (Considered the highest grade, usually special ordered)

“Center, free of heart” is considered equal to Structural Select, but less likely to twist.

For veneer, layered, laminated wood, and finish woods:

Lowest

E (Has the largest filled knot cutouts)

D (Not a visual grade)

C (Common outer layers of structural plywood)

B (Paint grade veneer)

A (Varnish grade veneer)

For mechanically grade lumber:

M-## (The number is the tested strength of the lumber in given units)