It boils down to how much you plan to spend. I went with a 2003 touring model non-brembo 350Z, for the luxury goodies (like heated leather seats not available in the "track" model), and then upgraded the brakes to better than the stock brembos as I do a lotta track days. As far as which model year 370Z or 350z is best for DD useage? Probably the newer the better, but that'll require more money. 370's have been around 2009, and haven't changed much during its entire run. The 350Z dates back to 2003, so they're gonna be significantly cheaper. But to find pristine unmolested 6 speed 350's that haven't been abused by young people that can now afford them is getting more challenging. If you're thinking 350Z, the early ones have a more jarring ride, so you might look at the better riding later ones if you plan DD duty. For commuting, I'd personally lean more toward 370 before a 350, but that's more $. fwiw, I'd also choose a G35/G37 for commuting before a Z. the G's more comfortable, and more practical than the Z with the same performance.
Enjoy.