I have 4 favorites:
Liquid leave-ins:
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Joico Leave-in: this is a great moisturizer and detangler. I use this daily to moisturize my hair.
KMS Silker Leave-in: this isn't as moisturizing or detangling as the Joico leave-in, but it gives excellent shine. I use this to wrap my hair, and my hair comes out sleek, shiny, and bouncy.
Creamy Leave-ins:
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Bumble & Bumble leave-in: softens and moisturizes hair. It's expensive but its very concentrated so you only need a little bit.
Rusk Smoother leave-in: I really love this. Ironically my hair curls up when I use this, but I do get smooth curls and waves (meaning no frizz), if that makes any sense. It doesn't straighten like I thought it would, given the name, but it does add softness, shine and smoothness to the hair.