The Aztek is certainly ugly, but if you can live with the neutering styling, it is somewhat practical.
The Niva is actually a pretty solid performer. Its indestructible and unstoppable.
I'd vote for the Ami 6 on my side. Uglier than the Aztek, severely underpowered, and weird controls that make it puzzling to drive.
http://en.wikipedia.org/wiki/Citro%C3%ABn_Ami