I have primarily run in 25 man raiding for the entirety of Cataclysm, and I raided all through Wrath of the Lich King and even Burning Crusade in 25 man raids. 25 man raiding is where I have the most fun. I like it for a variety of reasons. I enjoy having a wider selection of classes and specs available, I generally feel like a larger raid makes a fight feel more dramatic, I dislike how empty some raids feel with a smaller group. To me, a 10 man feels like a UBRS run. These are all personal reasons, I accept that they're not universal. I also wasn't impressed the few times I went into 10 man raids this expansion - the fights always seemed much easier, we blew through bosses we struggled with on 25, clearing 10 with undergeared alts due to the extremely forgiving space mechanics of raids like Firelands and Dragon Soul on 10 man.
World of Warcraft