

Though for ease of use fotoflexer is better. I really like the solid colors of befunky's Pop Art, but the grainy/gritt

The left is me driving in the Le Mans 24-Hour Endurance Race fifty years before I was born. Probably my proudest achievement.
Of the three, Photoshop is probably better for the professional. Adobe doesn’t even try to make it user friendly. I like fotoflexer for the reasons you mentioned. The premium features on picnik look really cool but if you don’t want to pay for them you end up tripping over them all the time but I use Picnik the most. It’s sort of my default photo editing site–mainly because Flickr links straight to it.