I actually own both Picasso Black Teams and Cressi Gara HF's. What can I say, I like black fins.
I've had the Cressis for years (very durable), but my ankles get pretty tired from all the surface swimming I do, plus the footpockets are a little narrow so I have to wear 1mm booties and my feet go numb from the cold.
The Picassos are less stiff and allow me to wear a 3mm bootie. They are a little flimsy when I start an ascent with negative bouyancy, but I'll take the trade-off for more time in the water.
If you find the Picassos too flimsy, you'll probably be happy with the Cressis as long as they fit your feet. The blade on the Cressis also has a lot more 'snap', not that you can tell underwater.
The Omer Millenium Comps are supposed to be pretty stiff, too. However, Omer footpockets don't fit me at all so I haven't tried them.