The chicken you use is personal preference, see notes below. Chicken Thigh  (Skin on vs skin off) - If you are pre-cooking then using skin-on thighs will produce added flavour, make sure to sear them well. Add chicken skin-side down to the hot oil, cook until skin is golden in colour, around 5 minutes. If you choose to skip the searing stage then I would recommend removing the skins as they can go a funny texture if added raw to the slow cooker.  Chicken Thigh (Bone in vs Boneless) - I didn't find a big difference in texture or flavour when using bone-in or boneless thighs in this dish. For younger children it might be easier to use boneless, my youngest certainly preferred it without the bones.   Chicken Breast - If using chicken breasts I recommend adding them whole rather than chopping them into pieces. They will fall apart easily and I suggest shredding the chicken (like in this slow cooker chicken curry). It will give a different feel to the dish but will still be delicious.