My preference:
AEM put out there EMS not too long ago, not sure if the STi version is ready yet though. Cost a lil bit more, but its a complete standalone computer as compared to the piggyback UTEC. Honda owners have been tuning on them for years, so i'm sure there are alot of people that can tune them. You can do pretty much anything you can think of with that monster, its a gorgeous piece of programming, and there is no wiring nightmare since it still plugs right into your stock ECU.


You basically pay for what you get. The Cobb setup basically consists of you sending them your ecu and them flashing it with their generic program for your mods and mailing it back. Problem is that everyone's car is different, let alone has different brand mods, so there is alot of power left on the table. There also isn't a very wide variety of maps. For this reason its the cheapest alternative.
Ecutek is basically the cobb tune reflash done for your car specifically. For this reason its more expensive yet it comes with no user-tunability. I believe there is hardware you can buy that will give you that ability (deltadash) but then you are basically getting a reflash and using piggybacks to make changes anywayz.
This is why so many have just bought the piggyback in the first place, UTEC, and it has been so popular.