Personally, I like Gemstone a lot better. You still get a kick-ass lot of character customization, and in your first 30 days with a character you can re-spec in a matter of minutes if you want to try out something new without having to go back to basics (if you want to learn a new type of weapon or armor in DR, it's back to ship's rats or other low level monsters). Numbers for combat and some secondary skills are displayed openly so you can see the effects of your skills upon your effectiveness. DR requires a lot of repetition and for some classes sitting around being lectured or lecturing others to level up. Granted, levels aren't completely game-breaking in DR, but it's possible to have the weapon and armor skills to kill most anything and still be low level because you never bothered with working secondary skill sets.
Now, in DR's favor, combat is more descriptive than number-oriented, being able to work up just about any skill can shock the heck out of somebody who thought based on your class and relative wealth (via look) you were something else entirely, and skills you actually use are indeed the ones you're best at. Levels are nice for the stat points, but you can get those from working up skills as well. It's fun to be able to pick your own boxes despite your class; and what's really fun (and I've been wanting to do for the longest time) is to have a low-level trader walking along the trade routes with a yak who sees the master thief dipping into their pockets, robs said thief blind while he's still recovering from the failure, and then walks right along. Of course, a trader can't learn those skills very quickly, which is what would make such an event so much more entertaining.
Being a number cruncher myself, I prefer GS, but I can't say I haven't found DR entertaining as well. I've gone back to both every so often over the years.