I use them both. Both have good points, both have bad points. I would advise to try both of them. I would HIGHLY advise you getting your specific year model's Ford Service Manual. This is 10X better than the other two put together!
I have both and always find them lacking.. I really need/want a Ford service manual! I advise you to get one also if you do very much work on your SC. I prefer the Haynes over the chilton because that's all I mainly every use and it is more year specific. The Haynes is 89-97 while the Chilton is 83?-97.
Is there a place to get a discounted Ford manual? The "Ford" manual is the same as the Helms manual, correct? I know there is a website for the Helms, but maybe there's a source that has them cheaper?