Having done both i would say that If your not keen on fat then I Dukan would be your best bet.
It's low carb/low fat/high protein.
I like the fact that you can include low fat diary in form of skimmed milk, ff fromage frais and ff yoghurt.
I also like the oatbran which I was very dubious of before I tried it - but there are lots of yummy ways to have your daily allowance.
If you have done so already I would read both books and decide which sounds best for you.