Definitely husband. I think the 'volume' of love is very similar, but husband has the edge. Then add into the equation that he is my life partner, my other half. My children, I hope, will be in my life until I die, but they will not share everything with me in the same way as my husband. I want them to live their own lives. The closeness between husband and wife in a loving marriage is another level.
I have had a stillbirth (which though horrific I appreciate is not the same as the death of a child who you have lived with and whose character you know), and whilst it was phenomenally painful, it did make me realise how enormous my love for my husband is.
I actually think that a couple who love each other primarily and greatest can provide a really good, secure "base" for children to grow up in. If I put myself in my child's shoes, I think I would like the security of knowing that my parents' love for each other was that strong. I don't think it's a negative thing. It doesn't make me a slave to my husband, or him to me. Obviously if my husband did things which were negatively affecting the children, I won't blindly agree with him. We'd sort it out. But that wouldn't make me love him less.
I think my love for both husband and child is unconditional. I will love them both until I die, and nothing either could do will change that. They could do things which would make me want to stop living with them (husband or adult children), or make me hate their actions, but the love would remain. The only difference therefore between the two is the partnership aspect, which makes me much closer to my husband than I can ever be to my children.