Well... umm... That's a loaded question.
The Impreza is a great car.
The WRX is a better car.
The STi is an even better car.
In general, they're all solid cars. I assume, since you're on clubWRX.net you're interested in getting a WRX or an STi, ie: the turbocharged Impreza. In which case you won't find anyone here not go "yea get one they're awesome!"
And indeed, my friend, they are awesome.
Help us help you. What year are you looking for? Is it going to be a daily driver? Do you want to do auto-cross or hit the drag strips? Do you work on cars and want to modify it yourself, or let a performance shop mod it? Do you want to stay stock? how old are you? where do you live? Do you like bunnies? More importantly, do you like squirrels?