What tone you like is of course an individual thing, but these kinds of side by side evaluations can be somewhat misleading.
The first thing is the EQ. This will work differently for different amps, an amp’s «flat» setting may not be «flat» at all, which is certainly the case with the Rumble. Therefore, if you try to approximate the settings of another amp by simply having similar knob positions, you will not necessarily get a realistic comparison. Also, the fact that you’re not getting a similar sound with a similar setting doesn’t mean that it’s inherently impossible, it will just require different settings. Some of the differences you mention may be due to that.
Secondly, there is the gain setting. Rumble amps differ from most other brands here, as evidenced by the fact that they will work fine with the gain all the way down. It’s therefore very difficult to match this setting with that of other amps in a reliable way, which could lead to a difference in sound.
Also, the clear/muffled comparison is always suspect, IMHO, and this does not apply solely to amps. If I roll the tone off on my P-bass, it sounds incredibly muffled right away - until my ears adjust. After that, it just sounds pleasantly thumpy. If you roll off the treble on any amp, that will sound muffled to begin with as well.
That’s not to say that amps - the Rumble included - don’t have a «baked-in» tone, most do. But most amps can also get a myriad of other tones with different EQ’ing. I can get a glass-clear tone out of my Rumble 500 if I want, but it’s more geared in the direction of old-school tone, which is what I personally prefer. It’s different strokes for different folks.