Aesthetic
This is by far one of my least favorite heads. The body is extremely well done, the head has a nose that only a mother could love. Skin choices are very limited. The sliders have no effect on the nose. The head is only available with the body.

Catwa
A very popular vendor of quality heads. Prices are 5000L per for a variety of choices. These heads have the most support for skins in Second Life at this time. This head is Omega compatible.  The skins installed in the head are from Clef de Peau. The “Daniel” model has a skin that works fairly well with the Aesthetic bodies even.

GA.EG
I really appreciate what this vendor has for heads. They have nearly all of the sliders for adjustments enabled. It gives you the freedom to make your face shape the way you prefer it to be. Though the limitations of 3rd party support options for skins in particular is disappointing. This head is Omega compatible.  The skins installed in the head are from GA.EG.   They offer Hugo Skins in the store that match the head tones.

Lelutka
I published a complete review of the Stan head.

Vista
A new option for heads from the fine folks at Vista Animations. The sliders do not allow the flexibility that the GA.EG heads offer but there is a Combo special for this head and very nice Gerard AO for 3500L ( even less with Loyalty discount) and the head is Omega Compatible.  The skins installed in the head are from Clef de Peau. The Gerard is the only mens’ option from Vista so far.