spells vs. magic items for a primary melee eidolon

[ohako]

So, I'm plotting out spell selection for a summoner that really relies on the eidolon as a physical melee combatant using natural weapons (shocker).

There are a bunch of spells that mimic the effect of magic items, especially the big 6.

Pro using magic items
you get more interesting spell choices, and you get more actions to use them rather than for regular buffs
you can upgrade magic items in a way where some spells don't scale

Pro using spells
you can keep your magic items for yourself
it's cheaper
maybe a GM would restrict a non-bipedal eidolon's use of magic items according to the Animal Archive

let's lay the apples and oranges on the table

amulet of mighty fists - magic fang or greater magic fang
amulet of natural armor - if you're using magic fang, then you could add this amulet, or you could just cast barkskin
bracers of armor - mage armor or shield
ring of protection - protection from evil or magic circle against evil
cloak of resistance - same as above
belt of giant strength - bull's strength or mass bull's strength

So, questions

1. Is it always better to use spells to mimic the big 6, and keep the magic items for yourself? Or the reverse?
2. If the answer to the above question is 'neither' or 'it depends', then what's your preferred spells vs. magic items layout?
3. Aside from the big 6, are there other magic item vs. spell choices that such a summoner would need to make?

[Claxon]

A bit of both.

Keep in mind that each spell you have to cast is a round the edilon is at less than the optimum of where you want them to be. Also consider what you need in magical items. If the edilon is your offense, you only need to worry about defense. And then you could provide the rest of your wealth as gear for your edilon.

One thing for sure magic fang or greater magic fang only affects one natural weapon (or you will get multiple +1 natural weapons). A amulet of mighty fists is basically required here.

Then consider spell duration. Mage armor will last effectively all day. Barkskin might be okay at 10 min/level, to get you through a couple battles. Ring of protection isn't really equated by protection from evil. Also, look at your edilons AC before you worry about it too much. The natural armor you get from levels makes it fairly durable on its own.

There is not an all encomapssing answer to say do all spells or do all items. It will probably need to be a mixture.