Both is great bass combo, just depend what kind of tone you are looking for.
Here is my story, i am a 15 driver lover, own Rumble V3 200/150 in past and move to Hartke KB15 currently.
Rumble V3 more close to Classic Vintage Vibe (Bassy along with some MID scoop sound)with flat EQ, meanwhile Hartke more clean flat EQ Voice along with better present Midrange .
If you love clean sound without any colour on your tone or you want/love to hear your bass pickup raw sound or you want your 5 string bass B string sound clean ,clear and solid or you always use pedal ..... Hartke Hydrive system will make you happy; if you love tube-like tone and classic overdrive sound, sure the Vintage button and Overdrive knobs on Rumble serve you well.
Hartke front panel is boring than Rumble which lacking of Overdrive, Vintage mode, AUX in....... she just a bass amp with clean sound, but those 3band EQ on it is more respond in tone than Rumble 4 band EQ.
Hartke Low pump in 70hz, increase the value you get thick and fuller Low without boomy; On Rumble i just get Bassy-Boomy on Bass knods pump.
The treble voice on Hydrive also different than Rumble. Rumble need the horn for treble voice support, when increase the Treble, i just get sharp sounding treble voice along with some hiss. On hartke, I can easily to tweak the Treble knob for "Treble voice present or tame ". Sure ,there are much lower Hi-Hiss with Treble boost on high master volume.
I dint play slap, but my friend who love slapping show me how the Shape function on Hartke smoke out the Contour + Bright + Horn On on Rumble when he play his GeddyLee Jazz at high master volume . To my ear , the Rumble is lacking something in the upper mid range and Rumble is No Ommph for slapping sound.
Dont fool by some guys here said Hartke Hydrive driver has metalic-tone, the hydrive driver sound smooth like traditional paper driver.
I am not Anti-Rumble guys or Hartke-Die-Hard fans, there are few great thing on Rumble V3 actually.
Rumble V3 have great Vintage Mode Voice which i still missing with, to get that voice, i need Zoom MS-60B.
The Bright Mode (horn ON)on Rumble can let your Elec. Guitar sound surprisingly good !!! Even fibre-ascoustic guitar. Rumble also let my keyboard and digital drum sound nice through AUX input with plenty of output volume.
There are some cooling-fan noise appear on Hartke, but still lower than Ampeg BA series. The Rumble is silent as mouse .
For the Bass combo look i prefer the Classy Rumble more than Hartke.
Have to mension again, that is my personal opinion on KB15 and Rumble V3 200/150 which base on 15' driver.
Dual 10 maybe different story.....
Thanks for reading.