My sister got burned by justfly. Justfly enforced rules that made the ticket completely non-changeable (it was not a Basic Economy fare, but may have been a consolidator fare). She had a medical emergency and had to cancel her trip. After some arguing, they offered an option to pay a $400 fee for a refund of the ticket, but they required the fee be collected separately rather than taking the fee out of the value of the ticket. After she paid the $400 fee via debit card, it took 9 month so and numerous lengthy phone calls to get the refund actually issued.

Just be aware that you may be dealing with a massive headache in the off chance that your trip is disrupted.

Disclosure: airline was not Delta.