Theoretically even 400W should be enough for an i5 6600/gtx 1060 combo. So, if the PSU is able to hold and deliver 450W you're fine. But in general; going with a good brand instead of a cheap one is the better idea.
If you're going for the h270/b250 chipset instead of the h170/b150 I'd take the 7600. This way you'll get native usb 3.1 support without having to deal with an external mb chip for that (and some other minor new features). You'll also get native support for ddr4 2400 mhz (instead of just 2133mhz). Not an enormous difference on its own, but when paired with the extra 200mhz CPU clock speed you'll get a noticeable boost for gaming. If you, on the other side, plan for the h170/b150 chipset, take the cheaper 6600 and the 2133mhz ddr4 ram (2400 won't work here). Not worth spending extra $50 for just 200mhz more clock speed, imo.
