Well, I've played both, but am more dedicated to Runescape. Of course, I prefer Runescape much more the Diablo. However, both games have quite a few differences. Diablo uses a 2D, sprite-based interface, like what I call the "2nd generation" video games. Runescape on the other hand uses a 100% 3D interface, like XD. This, however, has some outcomes opposite to what could be expected. Runescape's graphics tend to be polygonal and with poor texture, while Diablo's 2D system supports much more detailed ones. As far as gameplay, Runescape definitely has a greater variety of activities, While Diablo has only one objective and acitvity. However, Runescape takes very long to progress your character, and often gets boring. Diablo has a lot of gore, and Runescape has none. There are many other similar differences that make TRULY unbiased opinions very hard to give or find, for that matter. But, I will go with Runescape.