I have been doing the Focus28 diet for 3 1/2 weeks so far. I actually like most of the food - the entrees in particular. I ordered the Eight Week Program, and I haven't found anything yet that I really hate (although I don't think I'm going to like the Cream of Mushroom Soup or the Raspberry Hot Cocoa). Anyway, I'm down 7 1/2 pounds in three weeks (though I admit to cheating here and there). I've been blogging about it - maybe something there will help -
http://www.laineymarie.com/
Anyway, I can only comment on the Focus28 diet - I've never tried Ideal Protein or ProtiDiet. I was on NutriSystem about 6 years ago, and I didn't care much for the food. But, as I said, the Focus28 food is actually pretty good, and I'm pleased with how I'm doing so far.
Whatever you choose to do - Good Luck!