Realms of Despair, in my opinion is the best mud out there! There are a few reasons for this
1) There is always someone willing to help out whether it be just normal player or an immortal.
2)Its very rarely laggy and its very easy to connect.
3)The people are very friendly and always willing to have a chat.
4)It very newbie-friendly, with great help files which explain things clearly.
So, if you are bored or looking for a new mud.. realms is number 1!