HPTuners uses credits. Once you buy their hardware, they give you 8 credits. I have never seen a vehicle option qualify for more than 4 credits. You don't have to worry about a dongle, and I obviously can't speak for a product that isn't out yet but traditionally, HPTuners always has datalogging available when they release a product. They charge $500 for a package that doesn't include auxiliary inputs for datalogging and $650 for a package that does. Once you buy that, there is nothing you ever have to purchase unless you run out of credits.
So HPTuners gives the buyer a lot more for their money. With the module they send you, you can read codes and use credits on ANY vehicle under their huge umbrella. No need to buy additional units like SCT. I have used just about every software package for tuning vehicles and SCT ranks the lowest in terms of quality. HPTuners ranks the highest. I have to work around things in an SCT tune as opposed to HPTuners doing exactly what you ask the first time and their software is more user friendly. Hell, SCT doesn't even have their graphs working yet and a lot of the variables in the SCT software don't have units. Even on timers, lol. Hope this cleared it up a little.