I'd think that Shingen-Vohu-Saraswati-Ryu-Oh-anyone? Vohu and Saraswati compliment each other really well, and Ryu-Oh with Vohu hits -50%/-50% against Fire enemies. And gives you BP. Last slot is a wild card for anything that you want, like Cthulhu for back-up debuffs, Snow Raph for damage cut, Asherah for burst even more memes, Shiva for general damage output.For damage? The first one is Character Atk, the second one is Elemental Atk (as it doesn't mention Character). The super simplified damage formula is "CharacterAtk*ElementalAtk*baseAtk"
Confused? It means whichever you have less of. Since CharacterAtk is the same thing you get from your weapons (Assault), in general this means that Elemental is better. As a rule of thumb, always pick Elemental UNLESS you have all of this:
1. fighting with elemental advantage (because that gives you 45% ElementalAtk)
2. have an offensive Soul weapon (because that's ElementalAtk)
3. are using a 100% Eidolon
With all three and a good Grid, Character and Elemental tends to be about the same. I've made a damage calc for this, which may or may not help to clarify.
For survival? If you have fair amounts of HP or heals, the latter as it is -10% damage taken, but remember, only against Water.
And finally, reminder that Medjed has an active which is way better than Ygg's.