The Citabria (or most taildraggers) will teach you the most about very broad airmanship skills. Fewer and fewer pilots today are learning this, so it's an asset to have this background.
On the other hand IFR training will be more practical in a 172.
In the end - you'll want to fly several different types to have a well-rounded CV. Thus you should consider the rental route - you won't be focused on a single type.