I have driven the WRX and STi Hatch (used to work in same building as Subaru/Isuzu franchise)... the WRX really isn't my cuppa (felt almost Forester XT-like) and the STi while nice, is a bit soft for the badge and even the wide wings etc dont lift the styling enough for me. However, that sort of thing is personal preference!!
Depends which camp you are in regarding the Hatch/Wagon/Estate thing, however if you search for an Impreza on eBay or Autotrader then I'm sure the Wagons are listed as Estates.
Believe me, I'm not a Classic die hard (although my sig might suggest otherwise!! )... if I was ever to return to an Impreza, then I'd be going for another Hawkeye STi.
Cheers,
Grant