Actual the worst one of all is F2P/P2W. About Freemium, it depends on your attitude towards P2P. If your fine with P2P, freemium isn't that bad at all. If you don't like P2P, freemium isn't much better. But except you've got so much money, you don't know how to spend it, P2W is far and away the worst.
Well, I can't say I've played a P2W game, but the reason I hate freemium so much is that it calls itself "free" then forces you to pay to get all of the content. Paying for extra storage space? Not crazy about it, but ok. Paying for cosmetic items? Absolutely Though I do admit I absolutely HATE the way most of them use the gambling model- you pay a small amount for a "chance" to get a really cool skin. I realize that most people are svckers and will fall for this stupidity, but I want the cool skin too, and am willing to pay a flat amount for it, but they don't offer it that way. That's my biggest gripe with GW2's cash shop, in fact.
Anyway, if the game makes you pay in order to gain access to all of the content in the game, then it's not free, in my opinion.