Connecting a MacBook Air with Thunderbolt 2 to a Monitor with HDMI and USB-C
I wouldn't recommend any of those. Instead get an ordinary mini-DisplayPort to DisplayPort cable and connect the monitor with a plain cable instead of adapters.
The 2015 MacBook Air cannot be charged over the USB-C port in any case, so you cannot benefit from that feature of the monitor right now. However in the future you might have a newer computer, and then the USB-C port with Power Delivery might come in handy.