It's so random that it's a little vain to hope have this or that in the first parts of the game. Myself I like get relatively cheap items with leadership bonus in the first areas of the game so I could buy them easily soon enough. That's all the problem there's not so much choice in a same game so you rarely make choice.
Anyway here's an item list and why, but well reasons are quite obvious:
- Items that provide leadership bonus (list is too long so I don't quote it): Their leadership bonus is a huge bonus during first parts of the game so they are a priority and so cheaper are even cooler because you can buy them sooner. Later in the game only those with a very high Leadership bonus worth to be wear plus some that provide some additional bonus.
- Intellect Ring & Ancient Amulet & Banner of True Faith & Gladiator Sword: Some items gives something after n battle so buy and wear them asap make them a priority for me.
- Pendant of Iron Will: Another priority item to buy if I get it in a game and don't have the hypnosis spell yet.
- Well of Mana Belt: The mana regeneration bonus is very very nice and the item relatively cheap, only that make it a priority for me.
- Twinkling Boots & Slippery Cuirass: I agree with you that items that increase physical damage resistance make them a priority in first parts of the game. Later their bonus can be attractive for many fights but also at this point you often have more appealing choices and no slot for them.
- Items that provide int & mana bonus (list is too long so I don't quote it): For mage they are a priority and for any classes they are a top for two points:
- To reach some critical int level like 15 instead of 14 and have more choices of those items help adapt int bonus to other set of items you are using and int increase the character get.
- For a mana bonus for some fights. For example a fight you'll use for maintenance and more mana will make it cooler.
- Tactics Treatise & Bloody Band: Even if I don't always wear them if I want use another item for something else, buying it and try wear it are a priority for the xp bonus. Complete the set with the Tactics Treatise and the Bloody Band gives 5% more xp bonus, so I try buy it in priority but wear the Bloody Band only if I also wear the Tactics Treatise and don't want wear something else.
- Belt of Luck & Dagger of Sentence: Items that increase critical attack are very nice, I use them in priority except when enemy army includes Ancient Vampire then I need not forget remove them.
- Crown of Blackthorn: For any class I consider it a priority item just to slowdown rage decrease between fights and if necessary removes it just before a fight if I have something better to wear.
- Silver Chain Mail & Paladin Shield & Silver Rapier: Those items provide bonus against undead and that's a nice bonus during all parts of the game. You just need not forget wear them only when fighting undead.
- Boots of the Mystic: The boost to haste and slow spells can be very very nice and worth not wear another item more powerful.
- Ogre Sandals: Those are great to use with giants. In a game I even get two of them! Buy them is a priority for me so I could use them if I use Giants.
- Banner of Heroism: One of the item with leadership bonus and that's enough to make it a priority during first parts of the game. But also the +1 initiative to troops level 1-3 is dam cool and can offer some interesting choices.
- Wind Wings: Often this item is worthless during first parts of the game and it's rare to get it that soon. But there are many flying and soaring units and the +1 to speed can be a strong tactical bonus. For example if you use in your army Ghosts + Cursed ghosts that item helps throw them fast in fight and attract all the attention.
- Snake Boots: Royal Snake are an interesting unit choice during first parts of the game and this item make them even more interesting and could justify use it even if you don't use any other Snake.
- Jackboots: Just to use with Sea Dog but that can be enough to justify wear them. Later in the game that's less useful because you'll use better than Sea Dog.
- Griffin's Banner: The -30% Leadership for Griffins can be huge quite soon in the game and make it a priority if I want use Griffins.