from guide: Guitar Wood Types and Tones (Body, Body top, Neck, Fretboard)

Chapter 3. Guitar Neck Woods

Neck woods:

Maple:

The most common electric guitar neck wood, Maple has a uniform grain, it's strong and stable, and it has less reaction from environmental changes than other hardwoods. However, there is opposite opinion - maple is almost free of natural oil and it absorbs moisture from environment or sweaty hands line no wood else. As a result, neck is under risque of trouble, thus we coulnd't find maple neck without heavy lacquer coating.
Its tone is highly reflective, and focuses more energy onto the body wood. All things being equal, bolt-on Maple necks emphasize the body wood and are more of a factor on the guitar's jingle.

Mahogany:

The even density makes stable necks, and the open pores make the neck a little more responsive than a maple neck. The Mahogany will absorb a little more of the string vibration than Maple will, and compresses the attack and the highs a little.

Koa:

The tone is somewhere between Mahogany and Maple with a little sweeter top end.

Rosewood:

Heavy, oily wood, a Rosewood neck will produce excellent sustain while also smoothening out the highs. Generally with greater sustain comes a brighter top end. This is not true of Rosewood. It mutes the high frequency overtones, producing a strong fundamental that still has the complexities of mid and low mid overtones.

Wenge:

Stiff, strong, and stable, Wenge trims some high overtones like Rosewood does, while resonating more fundamental mids and low mids due to it's multi-density "stripes" combing away a little more of the mid and low mid overtones.

Learn more about Body, Body Tops, Necks and Fretboards at guide: Guitar Wood Types and Tones