Clearly it all depends on your driving style, if your using it around corners always and wanna have a manual I would go sti, if you want raw power/luxury and a badass car I would got SRT. Ive own a 07 STI before, great for beating the hell out of it, its quick but then your labeled as a tuner kid even tho your an adult. At least with a SRT you can piss everyone off cause a 4000+ lb car beat there little turbo charged civic.
Me personally I would go SRT, for the simple fact you don't gotta always play around with little tuner kids trying to race you 24/7 if you had the STI.
STI you will need to have a decent pair of coil overs to upgrade to since their suspension goes to crap fairly quickly, in the same breath so does a 300's front end, but to each their own
My vote SRT