It depends on what job I am doing. If I am sewing something thick like stuffed toy shut, I like to use coats and Clark button hole twist which is a strong thick thread. General hand sewing is usually ordinary polyester thread since it is strong and I don’t care what brand it is. If I am doing hand appliqué, sometimes aurifil or silk thread depending on the colour match. Hand sewing through thick fabric, I would probably go for a polyester thread for the strength as you will need to pull on it as you sew. Good Luck!