Signal strength differences between JT65 software

I had a little argument about how JT65-HF and WSJT-X receives. Paul PC4T thinks the JT65-HF HB9HQX version decodes better as WSJT-X. Hans PE1BVQ writes me via e-mail JT65-HF original (last) version decodes better as JT65-HF HB9HQX and returned to WSJT-X 1.3. Now, actually the original JT65-HF version will not be updated and I left it out at the test. I downloaded and installed the newest versions from WSJT-X, JT65-HF HB9HQX and JT65-HF Comfort. WSJT-X was set on JT65 decoding only, both JT65-HF versions both on BW100. What did I discover? Well, first of all the HB9HQX is the fastest decoder by far, it decodes seconds earlier then the comfort and the slowest WSJT-X. But which one recieved best? Well, look at the picture and decide for yourself. I left all programs running simultaneously for a few time slots. Sometimes WSJT-X was better, sometimes the JT65 HB9HQX version or the Comfort version. A little comparisation from what you see in the picture:

Program   Call received    JT65-HF Comfort    JT65-HF HB9HQX    WSJT-X
Timeslot
20:22       EU6PW           -8dB                        -8dB                            -1dB
20:22       M0OAB          -14dB                      -15dB                          -16dB
20:23       IZ5WRC         -9dB                        -9dB                            -4dB
20:23       IZ2ZPH           -7dB                        -8dB                            -6dB
20:24       EU6PW           -4dB                        -4dB                            -1dB
20:24       M0OAB          -16dB                      -17dB                          -17dB

Actually this is only a 3 minute time span. I left it decoding a lot longer and you should say average WSJT-X decodes most of the time better as it produces better signals. Though I think it's just a difference how the signal is calculated in the software. Just like 2 different rigs with different S-meters. You don't see much differences between the 2 JT65-HF versions. What strikes me is the following picture, it is just a example from something that happened a few times.

WSJT_X missed the signal decode from SP6ECQ (at DF 175). Now I know WSJT-X 1.4 is beta. But may be it's not too bad to run 2 different programs at the same time when decoding. I tried to run WSJT-X 1.3 and 1.4 at the same time but that doesn't work. The last program started will decode, the other one stops.
And so, now you think WSJT-X is a bad receiver.....look at the next picture and get confused.

So what do you think? This time the comfort version decodes DC3XD with -25dB. The other progs don't even decode anything from DC3XD. I switched to WSJT-X 1.3 this time. What is happening here and what is the best decoder now? I don't know....decide for yourself! Or better test the programs yourself!