[ReefDoctor]

The only choice for me is

GLASS !!!!!!!

The ONLY advantage I see to acrylic is its drillability.
The Durability of glass is unsurpassed, however when engineering a system pre planning is needed when choosing a glass tank. Getting the holes right for your application takes some forethought. Factory Pre-drilled or "ReefReady" tanks might not be adequate for all applications- custom factory drillied can get pricey but for me well worth the cost and effort.
One greatly overlooked draw back to acrylic is that even the highest quality tanks can have a hazy look, due in part to lighting effects either improper lighting or the "Fibreoptic effect" to properly lit tanks. This problem is not to uncommon and seems to be a tank by tank thing.
The temprature stability of acrylic can hinder you as well as help you depending weather you are trying to cool a hot tank; heat a cool tank or hold a tank a certian temp. (thats 2 losses and 1 win)

I have one acrylic 160 propagation utility tank and a slew of acrylic sumps for that application especially sumps I really like acrylic but for the main show tank I only use Glass and prefer Starfire glass for all viewing panels.