AD quints. Life steal won't help you last hit or poke, only sustain, and not by a good enough margin to sacrifice the 7 or so AD you'll be missing per auto on an enemy/minion and like 4-5 damage or so per skill.
Life steal isn't significant until late game, and by then you'll have enough items that the small amount you get from quints is irrelevant. The early CS is what matters, so go AD quints.
Also, life steal does nothing for skills. So all around, you're weaker and lose trades so that'll negatively counterbalance the tiny bit of extra sustain you have.
Edit: Missed the second half of your post. A juggernaut is supposed to be a hulking, tank like sack of meat that's job is to lumber at the enemy and soak damage while also dealing enough damage to be a threat. Sion, garen, morde, Darius. Typically, they're very tanky and lumber at you taking damage and trying to break a carry. Supposed to be kite able, but should they get to you, they break you.
Vi, Olaf, xin Zhao are supposed to be bruisers. They typically have some sort of heavy engage and build tanky and some damage. They output a steady stream of damage, not too much burst, but not super tanky as well. Now yes, build them full damage and they burst, but that goes for any champ. They'll die quickly if built this way.
Hope that makes sense.