I've tried so many.  Ended up with a Noco Genius 150 3000 amp.  They now have a 4250 amp model. Many that I tried said they would start a 6.7 diesel but in reality, they couldn't.  So, test why you buy to be sure it will start your dead battery truck.
Also, I found that these new types of jump starters will not start a dead battery.  The battery needs to have a certain level of volts to excite the jump starter.   So, like djevox above, I also carry a JNC-660.  The JNC-660 was recommended by a roadside assist friend who has used one for years for all of his roadside jump starting.   The JNC-660  has a regular lead-acid battery to do the work.  Like jump starting via another vehicle.