You are asking a community of players who (more and less) clearly prefer to play priests if a monk is better/more fun than a priest?
Not sure how self explanatory the answer would be there.
From a utility point of view I think most progressing guilds would prefer a disc, though monks have a few nifty tricks as well (revitalize hello), but the absorbs and dps utility a disc brings is still higher than a monks dps utility, not only due to pure numbers, but also due to the "being in melee" factor that a monk is tied to.
If you prefer melee dps and want to heal, well, you should probably play a monk. Is it more fun than a disc? I really wouldn't know if you find it more fun than a disc, I personally prefer playing a disc any day. (ps as a former resto druid Vanilla >> MoP I could point out that a disc can jump and run around more freely than a monk due to instant spells such as pom, holy fire/solace, glyphed penance, shields etc. So if you enjoyed blanketing a raid with a spell while being able to jump + enjoy the ability of being able to dps whilst doing so, I can recommend playing a disc, I've loved it).