Standard metric is above 80% capacity after 1000 cycles. Yours is above 77% capacity after 1700 cycles, that’s good. Is you want to make the battery last longer : don’t charge above 80%, don’t discharge below 20%. There might be settings in your BIOS or OS to do that.

I’m gonna say get the Inspiron 16. You don’t have to pay out of pocket, much a quarter the electricity costs for you compared to the Alienware, and you don’t care if you waste 10 mins a day waiting for the computer if you’re paid hourly.