I recently purchased my tuner/exhaust/intake and did a TON of research prior to doing so.
From what I could tell based on that research is that you really can't go wrong either way. Whether you get the Spartan Phalanx, or the H&S. Personally I went with Spartan. It seems that with the tunes that Spartan offers they have great DD tunes, the 210/250/275, and if you want a full on destroy someone tune they have the 310/350. They also offer several other tunes like the 210 tow tune and others that produce less HP if you are looking for that.
Personally with where I want to end up with my truck I like to have the ability to delete the DPF, and have a strong DD tune. Then at the track I want to be able to really kick someones *** if I want to. Also with future build plans the brute force of the Spartan tunes is what I want. With the Dashdaq that you get with Spartan there is also more monitoring capability, larger screen and data logging.
Based on my research, it seemed that H&S has many great tunes as well, but when people describe the tunes I really don't get the impression that I get when people describe Spartans 310 tune. There is nothing wrong with this though, I think H&S may have better DD tunes. H&S also has shift on the fly capability, something you don't get with Spartan. That is a big deal for most people. Also the daily drivability of H&S's "Big" tunes.
That isn't all the differences though, you are going to have to do a lot of reading and searching. Also, the information I just provided is not from personal experience, just what I concluded from my reading.
I currently have the Spartan Phalanx/MBRP 5" DP back exhaust/S&B CAI waiting for me at my house. Like I said, I felt that fit what I wanted to do the best.
Most of the time there is one product that is better. Here they are both good, you need to decide what is going to be best for you with what you want to do with your truck.