Having driven all three...

The Mazda3 is the least fun to drive. Not saying it isn't fun... but the steering isn't as good as the other two, and... four-speed automatic... it just doesn't have the goods to go.

The Mazda6 has the best steering and the most "buzz" when it comes to hooning around. Again, though... AT only. So you've got the best steering on the market (better than the NC Miata), but you don't have that fine control over your speed.

That generation Focus has fantastic steering. Not quite as sharp as the Mazdas, but it has that sublime touch you get with the great ones, like the dual-wishbone Accord or the Lynx.

Hard decision... personally, I'd go for the Ford, because at least I know what to watch for and where to get it... and given how I drive nowadays (strict 80 km/h... only once a week past 160 km/h... no heavy braking... proper warm up and cool down... etcetera), I can make it last a long time.