Krieg Death Knights are usually recommended to beginners for good reason. Its still very strong and the set can be target-farmed. Mindwarps are BiS but lacking that, you can farm Theodin’s mace as a substitute.
This is an AoM guide but is still relevant now. Only a few adjustments needed. The guide claims 9 min crucible but with practice, it can be done in around 6-7 mins.