I bought the VX5000 first And it is a good machine. It did most everything I needed and I did not run out of steam very often. I used the hit water injection mostly on engines and door jams. I bought the Hill Injection because I wanted to try doing exteriors. The increased heat and pressure over the VX is impressive and I have used it on several exteriors. I use the hot water injection on heavy dirt, wheels, dirty tires and wheel wells.
I did not use hot water injection on the nasty console of this car but did use it a lot on door jams and wheels.
All three if the machines you are considering are good machines. If I had it to do over, I would have gotten the Hill Injection and never looked back. You have to fill it more often but it heats up fast and puts out tremendous steam.