My .02 is Trutrak at the top.  Quick to glance at it and you can steady your
hand on the glare shield if you need to adjust the AP during bumpy weather.
Also, my throttle quadrant, tank selector, and gear switch are near the bottom.
I don't like having put my hand in that area especially in bumpy weather.  So I
wouldn't want avionics that require frequent touches to be at the bottom.

Matt McManus
LNC2 360