the Bertoia's are my favorite also. the Bird in particular. to my eye, it's the most beautiful of the bunch and it's fairly comfortable.
Also, in the "modern wing" vein is the Wegner Papa Bear chair. I've never actually seen on in person though so I can't speak to the comfort but I think they look great. it's decidedly more danish flair than some can take though for sure.
As Matt said, one man's ceiling is another's floor in terms of comfort on any one of these really. At over 6 ft and rather "solidly" built, I do not find the Egg comfortable. My GF, is 5'4" and finds it quite nice. I will have one one day because it's dead sexy but it's not on the top of my list because it's just not built for me.
The ball chair, though quirky, is not something you want to sit in to watch TV or have a conversation since the ball blocks out a lot of peripheral sound. i think they're mostly conversation pieces. put one in your house and I bet you'll find it's the last empty seat in a crowded house.