The Kong Fiffi is probably the longest selling fifi hook on the market. It's a time-tested design that many Yosemite climbers have used and loved. It was my first fifi hook and I would still reach for it today. I don't know why Kong spells Fiffi with two f's. It makes it confusing when you search for it on the web pretty much everyone else spells fifi with one f.
If I had to buy a fifi today, I would probably get this one because it is one of the cheapest, I have used it a lot and I'm comfortable with it. That said, if the sewn runner on the Black Diamond Fifi Hook is the right length for you, then you might go with that one because it is light and comes in cool colors. I would also give the Petzl Fifi Hook a look.