(In-line quoting because you brought up a ton of different questions
What makes the DevaCurl conditioner your HG?
My hair craves moisture too (and loves thicker/richer conditioners), but the One Condition just didn't cut it for me. I felt like I had to use a ton of product to get the level of condition I needed compared to other conditioners.
One thing you could try is using the One Condition mixed with a deep conditioner - you'll use less of the more expensive product, but still get the level of moisture you need.
If you're looking into oils, another one to check out is Avocado Oil (you can find it at Whole Foods and other grocery stores). I know a lot of people swear by olive oil, but I found avocado oil absorbed better and felt lighter in my hair.
For super moisturizing products, I'm loving a pre-styling product called Marshmallow Moisture Balm
). While it is an online product, it's completely unscented, can be bought in huge quantities, is reasonably priced, and moisturizes like crazy.
Unfortunately the majority of the deep conditioners I use are either $$$ or have a silicone in them, so I don't have a good suggestions for those
Silicones are only a no-no if you've cut out shampoos:
As most silicones are not water soluble, they require a harsh sulfate to be removed. Since the CG method has you cutting out all sulfates from your routine, you no longer have a way of removing these products from your hair. This in turn results in build up over time that weighs down the hair and can prevent moisture from penetrating.
Here's some articles on the subject here
that you might find interesting.
I hope that helps some!