Which is more profitable – an MMO with a monthly subscription or a free-to-play game?

If you sum all of this up, I donated about a hundred dollars over a year of playing. And since I donated rarely and only when necessary (like, "oh, there's a good item at the auction/in the shop, I should buy it but I don't have enough coins!"), it's a very small amount, especially when compared to the amount of money other players invest.
A six-month subscription to World of Warcraft costs 359 rubles, which is a little more than ten dollars, if I'm not mistaken. You can draw your own conclusions from that.