Welcome to the forums.
"It depend on part on you, your budget and physical build, the intended use, and the intended environment. "
I made one from a piece of 2" x 18" x 3/16" 3V. It has a 13" blade, stall mat / micarta handle.
The grind was full flat for about 70%, then convexed. It is very sharp and can hack through 2x4s etc.