Where do you live? JMO - but given that the LB7 has been sorted out really well for a long time, I'd be inclined to go with whomever is closest, be it Nick/Bob, Rob, Mark, Tony, etc.
I've never ran any of their tunes, nor do I really plan to, but I do enjoy the content they put out on their YouTube channel as well on their DieselPerformance Podcast
Question, not sure if it is Duramaxtuner or if others do the same, he advertises a "modified stock tune" instead of just leaving it alone with just the emissions deletes. Don't you want a stock tune for diagnostics such as checking the health of your injectors..??