i believe AEM can do essentially everything the hydra can do, just without all the wiring complications. When i have $1800 i will be going AEM. The only reasoning for this being that i have friends that tune with that software and i've seen it and its quite impressive. I think it is always an advantage to be able to continuously tune your car till it reaches what you believe is perfection. Of course this comes with the liability of destroying your car, but that is the cost you pay.
Personally i believe EcuTek > UTEC when you compare what they were designed for. Although many of people have run higher numbers with UTEC, it will always be a piggyback and therefore limited in what it can do. EcuTek is also limited since it relies too much on the oem ecu, but atleast it retains all of the factory safeguards (factory reliability) and doesn't rely on an assortment of signals trying to fool the stock computer. I believe if you want your subie tuned and you are going to leave it alone, get a mail order reflash. If you have a tuner nearby that can reflash your ecu on a dyno (mastro) do that instead for higher #'s. If you want an ems that you can tune on the fly, with endless options, get an AEM/Hydra/Microtec.