Giant bikes in general are hard to beat for value. Of the three you've listed, all three have the same wheelsets and two have the same tires. The Giant City has the lowest grade of component selection (crankset, drivetrain, shifters, brakes, but is still a pretty good city bike.
The Roam has a front suspension that you really don't need in the city, and its not a great fork anyway. The Seek has identical components but slides in hydraulic brakes in place of the front suspension on the Roam. Long term, the Seek will offer more trouble-free driving miles with the least expense. It's the most expensive but delivers the most PRACTICAL value.
For a city commuter my choices would be the Seek first, the City second and the Roam last. Not that the Roam is a bad bike - but its a better choice for someone doing at least a little off-road.
Yeah! thats right, i went a step ahead and got myself a higher model.
I compared Seek 1 and 2 and saw that 1's component are three (or two?) levels higher than that of 2's (Deore lx >>> Acera). And that came for only 150$ extra.
Well, I didnt really like the dull bluish-grey colour of Seek 1 though. But couldnt find any other similar bike that could match the value of Seek 1.
And when I checked, saw that 2012 black seek 1 was waaaayyyy better looking than the 2013 model. I really wonder why did Giant re-design such a good looking bike.
So did you find a 2012 Seek 1? That's not paint - its a black anodized finish! I bought two of those myself for the girls in the family. OK - I had to put some pink on them to make that one fly - its supposed to be a MAN'S bike!
They had only one 2012 Seek 1 left. But that was a small size one. I needed large size for my height.
Also, what do you think of the stock tires in 2013 seek 1 (Giant S-R3, 700x32c)? Are they suitable for little bit of gravels and trails? A friend of mine has got an extra pair of Schwalbe Marathon green guard originals 700x35c. He offered both for 50 AUD. Is it worth to get them for my bike?