It all depends on if you have prior federal service that will add to your retirement. I've got several buds from the CG who are now SA's and are looking forward to 30 yr+ benefits when they retire from the FBI. One does RICO work in Philly, one has been to the sandbox twice as SA In Charge in Jordan and Kabul, and one was a helo pilot that really doesn't fly that much anymore...but they all love the work. Just depends on the level of sacrifice you're willing to endure based upon " the needs of the service". If you don't have prior service to act as a retirement multiplier..I'd recommend Delta.
Just my .02.
Welcome aboard if you choose the Big D..