My natural hair is anti-protein, but it's colored so I DC often with it, anyway. Bedhead's Dumb Blonde is my absolute favorite. It's a protein condish but it's sooooo moisturizing. Sometimes I get greedy and use it 2x/wk. It smells good, too.
Giovanni Smooth as Silk runs a close second. It doesn't have the moisturizing effect, but it leaves my hair feeling really strong.