Having owned Matrix1000 and still owning DW8000 (I have no opinion on polysix as I have never used one), here are some thoughts. In my opinion, Matrix1000 is not very lush sounding but more of that in-your-face kind of thing. I might change my opinion if I had a chance to work with it again, but that was the impression I got years ago. The oscs are bright and brassy in a good way, and the filter is also kind of general sounding, not a especially very warm or smooth one. A bit like some of the the modern DSI stuff (like Mopho and alike), it has it's own thing going on and I would not call the core sound lush. The strength to me was that it was easily audible in a rock band mix.
DW8000 has digital oscs and smooth filter, and overall it is a very simple synth. I have made an ambient album with DW only and used it also in a rock band context, so it definitely does not suck, but it is a very limited machine. At least my unit is noisy, there is an audible noise floor you have to deal with in a modern production.
An analog poly for ambient pads in a 1500 range... There are plethora of options these days, but I would vote for either Korg Prologue 16 or Roland JD-Xa. Both of those host a really vast variety of analog and digital oscillators (Prologue even has the DW oscillators available if so desired), lush analog filters and audio path capable of saturation, and tons of effects that sound good. Both of them have their own quirks, but I would consider those way more flexible than M1000 or DW8000, and still capable of doing similar sounds if so needed. Novation Peak might be a contender, if modules are ok. I would be interested to try out Take5.
But of course, it is it's own thing to work with old machines, so there is also a value in working with M1000, DW8000 or Polysix that the modern synths can't touch.