Do you drink a lot?
I ask cause I am a rambling long winded guy... and you lost me somewhere along Prius and MPG.
Of course most everyone here will say GTI. I'll wager anyway.
In the same situation I'd get rid of both and buy a car I love to drive everyday. Life is too short to spend any effort worried about MPG. Barring Full size GMC 4X4 at 8 mpg anyway.