[Willy]

As long as you needn´t a sealed suit, I would buy a full plate, possible of the best available material.

Than you can have it bolstered up via enchantments. The Classic Magic items series has some nice ideas for armor with enschantements. But add selfpowered, so you needn´t to cast all the spells on your own FP, maybe with some Powerstones build into the pieces, on the inside of course, for more power if necessary, and very important Fortify and Deflect, together with other protective spells. If you face ultra tech enemys they will laugh at you only once if you take Reflect Energy, Reflect Missile etc. Lighten is also helpful Full Plate IS heavy.

Also most high tech armor has some sensory equipment, this can be simulated via spells that augment your own senses. Not to mention that magic can tell you if someone is a enemy even if he is playing your friend or ally.

The counterpart of sensors is equipment which allows you to move undetected, here invisibility, blur , camouflage and much more spells help you a lot.

Remember you can enchant the whole suit piecemeal and needn´t to put every enchantment on every part of it.

Oh don´t forget enchantments that let you fight better, even more by adding some build in wands with explosive fireball, lightning, sunbolt etc, dont forget self powered!, you can also simulate the firepower of such a battlesuit.