Just have in mind that going via a third party/travel agency in a lot of cases means that they are responsible for you when it comes to rescheduling/cancellations/refunds etc.

I am unfamiliar with Justfly, but there are several cases through the past years where people have been stranded or not getting their money back because of all the schdule-changes and the travel agency they picked are close to mission impossible to get in touch with. However a good TA can make life much easier than dealing with the airline directly.