If you want to morph drum sounds on the fly, you’ll probably be interested in the Rytm’s performance mode, which is kind of its answer to “control all” on the MD, or the crossfader scenes on the Octatrack - but I think it takes it further than either.
What you can do here is assign 48 parameter changes - pretty much anything you can tweak - to the 12 pads, in any configuration you like (48 changes on 1 pad, 4 changes on 12 pads etc). Then applying pressure to the pad will morph smoothly between the current value and the pad’s assigned value. So one pad could apply a high-pass filter to all instruments, variable by pressure, while another increased the reverb send and a third pad increased a few LFO intensities or speeds, or sample start points, or all of the above. You can apply all the pads at the same time, if you have the fingers for it.
This is an incredible, monstrously powerful feature if you’re into live performance. It takes some setting up, but once everything is in place you can take a single bar pattern, or just a single sample, and tweak and mangle it in countless ways.
And you also have the scene mode, which is a similar setup - 48 parameter changes across the 12 pads - except you can only have one scene active at a time, and they change instantly. So you can use this for pattern or instrument variations, or indeed you can play the scenes on the pads in real time.
If you can get your hands on a unit to test, just check out the scene and performance setups on the test patterns - they’ll give you a good idea of the possibilities. All the machines you’re considering have their own charms and strengths, but if your goal is on-the-fly sound manipulation, the Rytm is a definite strong contender.