Some shenanigans: be an actual possessed suit of armor, rather than a statue. Be riveted together, if your DM insists that each piece is a separate object (this will make you one giant piece of armor). For one, this makes you immune to sundering if you're worn by an animated undead (which should be mindless, and commanded not to resist the movements of the armor) or an inanimate corpse (if you go this route, you can magic it up with things like Continual Flame to mislead your opponents), though in this latter case it will probably be ruled that your body is not equipment and you can therefore be destroyed normally. If your DM ignores this stupidity and allows armor to be sundered, consider Aurorum as an alternative material if you have buddies who can reassemble you if you're ever destroyed. Hardness, Matter Manipulation, and Augment Object (the latter should be applied by making the armor a magic trap that casts that spell on itself each day) are all useful. Also consider carving Symbols onto the armor; I recommend Fear, Pain, and Insanity, but they're pretty much all good when combined with the Permanency spell.
Also, both ghosts and unbodied liches are good race choices; very difficult to destroy permanently, and all the shiny benefits of the incorporeal subtype (including the rules in Libris Mortis that let you give your body Concealment and have your body grant you Cover if you occupy its space, which come in handy if you need to manifest).