I love Surgebinding due to its complexity as a magic system, method of acquisition (it's based on merit rather than something some people just have), personalization (the Orders!) and how the spren remind me of dæmons from His Dark Materials. It just offers so much: boost in strength & stamina, healing, a weapon, armor, companionship with your spren, a chance to meet like-minded people within your Order
I also love Forgery because of its complexity and the idea of reality hacking
I like Hemalurgy because of how menacing it is, and how costly it is. Also, stealing part of someone's Spiritweb just sounds so badass.
I don't really like BioChroma. You can't really do much with your own Breath except to give it up. Many, many others have to give something up, something that is almost inherent to them, in order for the magic system to be usable. Only after acquiring a lot of Breaths does one get access to perks like the Heightenings and is able to access the magic system of Awakening, and the number of Breaths involved to get there just doesn't sit right with me (Yeah, I know, this view is quite contradictory with my views on Hemalurgy, which also requires harm to others but this just hits closer and feels more "real" to me somehow). I don't really like the idea of Returning either, becoming kinda like a vampire, subsisting off of people's Breaths, with the sword hanging over your head that your dying (again, I might add) could do more good for the world than you continuing to exist. That's just messed up. Also, the Lifeless, that's just necromancy