I did 14 days straight on a water fast followed by 7 more on juice.. (only stopped due to health concerns) The first 3 days are bad. Then waking up is also bad. But beyond that it was a pleasant experience. I went out to eat with my friends, had a normal social life, just happened to be the guy on the water fast. I got a lot of extra attention too
I did a juice fast the year before (juicy juice pasturized junk). Made it 6 days and succumbed to hunger. I was constantly hungry on my juice fast.
I've gone vegan for 30 days before which was tricky figuring out what to eat. I mostly ate soy milk + grape nuts cereal.
I've eaten nothing but chicken, spagetti, and salad for an entire summer. (lost 60 lbs)
I've managed to go 5 days on the Raw food diet before.
Overall I would say once you get the technical "what to eat" aspects down, and give your tastebuds time to adjust, switching to a different "lifestyle" of vegan/raw is a healthier choice than water fasting. However, remaining on a water fast is very simple due to its dogmatic approach and the cessation of hunger after 3 days.
Switching to vegan/vegetarian/raw is a change in what food you eat. Switching to fasting is a change in eating. I find its easier to turn off eating than it is to change it.