Originally Posted by Framer
Good - I've always had good luck with Cummins B series. I know for a fact in the 1998-2005 time frame the Cummins 3.9 was cheaper than a comparable hp Deere 4.5. Much more common, easier and cheaper to fix. Many parts common with the 5.9 in the Dodge trucks and CaseIH equipment. I have had some good experience with the 3.3 and have heard nothing but good things.
Bad - The pull/hold fuel solenoid on the inline pumps fail frequently, but they are easy to fix. They also don't have a balance shaft, so they tend to be hard on exhaust systems and motor mounts. Some of the Tier II motors (approx 2003-08) can be cold blooded if the battery isn't up to snuff.
I can't complain about the Deere, but I don't have nearly as much experience with them. The Deere comes with sleeves where the Cummins is parent metal bore - but this is only really important if you plan on keeping it long enough to get into a rebuild. I believe the Deere also has a balance shaft, so your exhaust system should last longer. The Deere's are also a little quieter.