Mesh Heads are the rage at the moment. The only drawback, most can't be modified except for size and eye position. Bento, the upcoming new skeleton for your avatar, makes mesh modifiable and allows you to personalize your mesh head almost to the extent as the classic avatar head.
I say “almost” because certain sliders on this Bento enabled new Mesh Head from AK weren't doing anything, others, like for instance the slider for mouth corner position, didn't let me put as much of a smile on my face as is possible with the classic body so that I still look a bit sceptical, lol. But then, who wants to look like the Joker?
Still, as you can see, the possibilities are vast. I use the same Marco Mesh Head from AK on both pictures, the same skin appliers and the same hair, although I use a bit more beard stubble on the right picture. On the left is the way you can use the Marco Mesh Head at the moment, modifiable only by choice of skin applier and/or skin tone. On the right is my personal interpretation (i.e. shape) of Marco, an attempt to make him look more mature.
Before I forget, with Bento you can also change your eyebrow shape using the classic "baldies". I only found one I like after I took the pictures, so here I use no "baldie".
But, best you try it out yourself. Get yourself the demo version of this AK Mesh Head, download the Second Life Bento Viewer (version 188.8.131.520815) and start playing the sliders. Have fun!