for naturals, medium<short<long...i loved my TWA and even though im out of TWA phase its still too short to bun or ponytail so im stuck in WnGLand or Puff Paradise...with medium hair you can WnG, Puff, Twist, Ponytail, Bun Etc. its so versatile, and doesnt require as much maintenance and time to detangle, moisturize or style as long...
for relaxed hair i still think medium is easiest, but long hair is easier than short hair because (atleast to me) when relaxed hair is short it always has to be on point...u cant wear a puff or WnG b/c its straight so u have to constantly flat iron or curl it...atleast if its medium or long for the most part you can wrap it or pin curl it at night and just take it down in the morning