I'd find it hard to understand anyone who's used to a Golf even considering a Polo / A1 sized car (sporty variants or otherwise). They might be a bit of a hoot to drive...
... I doubt I would get tired of a car that was fun to drive. And the Golf is getting quite big. Some reviews have said that the Polo GTI is closer to the original GTI experience.
My experience is that small cars with big engines are very enjoyable to drive.
Our A3 was bought for comfort and economy, not performance. I love driving our A3, but experience has shown me that I would soon get bored of it.
Experience has also taught me that firm suspension and low profile tyres are not ideal for my local roads.
... this all brings me full circle back to another Golf, in my continuing quest to find the best car for me.
Mk5 1.9 TDI - very comfortable, but boring.
Mk6 GTD - enjoyable to drive, but quite firm - even with adjustable suspension.
Mk7.5 GTI PP with DCC - I'm prepared to accept the loss of economy and some comfort, for the gain in performance.
(then maybe a Mk8 Golf R, but a lot could happen between now and 2020)