I can't really say I have a "favorite Lego color". Brown is my favorite colour outside of LEGO, but with lego that applies to brown, dark brown, tan, light tan, dark tan, and brick orange.
My thing is color combinations. Many of my MOCs are the result of me wondering "how would these colors look together" or "can I make a MOC with these colors." Some of my favorites that I've tried are:
burnt orange and green
Dark tan and purple
Sand blue and Dark blue
I do have some least favorite colors though. Three, for different reasons. Tea green: I just don't like how it looks, kinda an ugly colour IMO. Burnt orange: it doesn't go well with many other colors (though green works) Silver: okay, so I mostly just hate this one because Bionicle and HF overused it way too much, but I also find it kinda bland.