Head

Cannith Goggles(D365,11)

You can't use the power, so it's just +2 to perception.

Casque of Tactics(AV,4,14,24)

Scaling bonus to initiative... which won't keep Martyrs in the hunt, but doesn't hurt any. But the daily power might let you go first if you need to. Or more likely, let your controller go first when they need too, but you rolled the 20.

Coif of Focus(AV,21)

'Spensive, but those conditions suck. If you and your DM are playing Rocket Launcher Tag, you need to be able to shed those conditions. And this will let you. Don't let the monster get another chance to apply it. Assuming a reasonable length work day, and some spike potential, you'll probably prefer the Coif of Mindiron , because it's "just kidding, not affected" power is an encounter power.

Coif of Mindiron(AV,8,18,28)

Snap Out of It , the item power. Encounter power too. Higher versions shed more conditions. If you find yourself grinding it out, you might prefer Coif of Focus \'s bonus to saves.

Crown of Stuttered Time(AV2,28)

Walk through walls (and take half damage) for a turn. Or for as long as you want to keep taking damage. +2 to Will is a nice bonus, but it is very expensive.

Goggles of the Hawk(AV,17)

This is actually a Godly item. But most DMs won't actually play it as simulationist as the item assumes, and thus basically will nerf it out of existence without realizing they are doing it. If your DM is more simulationist, take it. But I'm not sure why those DMs are playing 4e, and not Gurps.

Goggles of Night(PHB,17)

Seeing in the dark is never overrated. However ... campaign dependant. If your party includes a bunch of humans without darkvision, less needed... because someone's going to pop a sunrod. As a general rule, any time the encounter takes place in darkness, that's because your opponents already have darkvision, so it doesn't actually help you get an advantage, and sunrods are cheap.

Helm of Ghostly Defense(PHB,22)

Once a day, probably don't die. Half damage for a turn is good for martyrs, and this is a new slot to use to get that power. Necrotic resistance doesn't suck either

Horned Helm(PHB,6,16,26)

Part of the standard Charging package. You'll know if you want it.

Helm of Able Defense(AV2,14)

A final +2 for MoDs to use to move off the d20. And it's to all your defenses. Just be wary of Auras, they'll suck.

Ioun Stone of Insight(MME,21,Rare)

Frees up your arm slot if there's something else of interest to you and gives +4 to Perception checks.

Ioun Stone of Regeneration(PHB,25)

Regeneration 10. At this level, that should be more about saving healing surges than actually saving your bacon.

Ioun Stone of True Sight(PHB,28)

Nice bonus to Perception. The Darkvision is a decent effect, but see my commentary on Goggles of Night . The Daily Power... well, with luck once a day is all you'll need that.

Ioun Stone of Sustenance(AV,21)

The style play. Because you can't be bothered with trivialities like eating when you're tracking someone across the desert, and you're not already a Wilden, Warforged, or Revenant.