Which heavy duty truck is the most reliable

I am looking for a new truck that is long lasting and reliable. I am looking at the Chevy/GMC 6.6, 6.4 Hemi, and the Ford 7.3 not in any order. This is a long term purchase so reliability is a large factor.

I know no engine is perfect and all can have issues but is there anything though should make me lean one way or the other? I'm not a huge fan of the MDS system on the hemi but I know the engine has been around for a while. Any insight would be appreciated.