I would be biased if I said SCT, but that is because I am most familiar with it.
They ALL make mediocre "canned tunes" a one size fits all strategy. to squeeze the most bang, you will need to be semi familiar with the tuning process, or hire a local dyno tuning shop, to set the tune up for YOUR vehicle.
Things like tire size, rev limiter, shift point, ect ect, are very straight forward items to change, using your pc and the software.
Making the power is not so easy, finding where it likes the timing curve and the ping point. Don't let any one fool you into thinking this is a fuel economy device. As a matter of fact, fuel has little to do with power when using these tuners.
If you want a canned tune, buy any of them, they re all good for 10-15hp.
I don't own a hemi ram, nor do I own a "flash tunable" vehicle, but have used these on dynos for other people.
I do have friends with hemi trucks. One of the best bangs for the buck is 3.92 or 4.10 gear set. Even the long tube headers did not make the improvement that the gearset did. His next mod is either a comp cams xfi268 cam or a 6.1L srt cam...