what are some of the best builds to ensure that you get decent rolls and the whole party isn’t annihilated at some point?
Okay, so, durability? Here goes.
For your fighter:
Eldritch KNight 6 / Abjurer 6.
Focus on Abjuration spells only, and keep those wards up. Congratulations, you are now unkillable.
For your Cleric:
BattleMaster 4 / Life Cleric 8
Stack items that have 'on heal' abilities, most notably Zevlor's Gauntlets; providing Blade Ward at no concentration when you heal something. There's also an amulet that gives poison or acid damage to weapons when someone is healed. Obviously give that to either thief or fighter.
For your thief:
Gloom 3 / Assassin 3 / Battlemaster 6
This character isn't THAT tanky, but among the best archer builds, sruvives via stealth. Good caster for longstrider, too - giving your party some extra mobility.
For your Wizard:
Technically another Abjurer, that's the tankiest. I rather have control/damage on my caster. Just give him Mirror Image for survivability.
But, Arcane casters are stupidly easy to build in BG3. Tempest 2 / Storm Sorc does insane damage and fly away at no spell cost.
Pure bards control the whole battlefield, but are a little tricky in Act 2.
Evokers can nuke everything without ever harming your own guys; let those fireballs fly!
