It's pretty close, but I have to say farming, because I have tried getting lvl 99, but I gave up quickly. First off, there is much more people with 99 slayer than there is people with 99 farming, shows something. 99 slayer can take more or less time depending on how hard you train it, whist in farming you're pretty much stuck by how long your crops take to grow. 99 farming can be speed up a little by buying and planting a lot of fruit and normal trees, but from lvl 70 to 99 by example, it would cost something like 80M. To get 99 farming, your forced to spent a lot of money, you have no choice whist slayer is totally free and can actually make you gain a little money. 'Nuff said.