1. Do you have a crossbow press to work on your purchase, or will you have to take it to a shop for service?
2. Are you going to be happy with something you just sight in and hunt with but don’t shoot much?
The 440 seems to be getting good reviews (better than the 515), but still is a high performance crossbow that needs experience to maintain.
The Sub 1 XR is the only one of the 3 that can be rope cocked. It is in the middle performance wise. It can be maintained without a press, but that process is a bit laborious. They tend to be heavy and front heavy.
Rev X is getting nothing but outstanding reviews. I have held one and the balance is excellent. Crank only, but excellent system, like the Ten Point. Super easy maintenance. It will be the slowest of the 3 but still far more than sufficient.
Best thing to do, IMO, is to go to a shop that has them and handle (ideally shoot) each to make up your mind. Best of luck with your decision.