Just my 2 cents. Let's compare apples with apples, all prices RRP (I doubt percent discounts this year will vary much between brands):
Roco BR 50.40, AC with sound, 399€. Märklin BR 50.40 Insider, AC with sound mfx, 429€
Roco: plastic body, metal frame, can motor in the tender, speaker in the boiler, Loksound. Märklin: metal body, metal frame, Maxon motor in the boiler, speaker in the tender.
Since Brawa and Märklin and Brawa don't overlap models, I'll compare the BR 19.1 with the BR 01 (they did the same job in real life)
Brawa BR 19.1, AC with sound, 599€. Märklin BR 01, AC with sound mfx, 419,95€
Brawa: metal body, metal frame, can motor in the boiler, speaker in the tender, Loksound. Märklin: metal body, metal frame, SDS motor in the boiler, speaker in the tender.
Roco 110.3, AC no sound, 214€, Märklin 110.3, AC mfx with sound (not "full" sound) 269,95€
Roco: plastic body, metal frame, can motor, Lokpilot. Märklin: metal body, metal frame, mfx, can (unknown type) or SDS motor
Roco ET91, AC no sound, 214€. Märklin ET91, AC mfx with sound (not "full" sound),299,95€
Roco: all plastic, can motor,Lokpilot. Märklin: all plastic, can motor (I feel that here, M version is way overpriced)
If we go Fleischmann, prices are usually higher than Roco's and similar or more expensive than Märklin's in the same or comparable models.
BTW, I will also not buy motor-downgraded models at the same price as before, but will not go Roco to compensate. I'll go for the older versions.
As for the change from SDS to bell-shaped-armature motors, i.e., Maxon, Faulhaber, Portescap, I'm all for it.
So, take your pick, but I do believe that Märklin has still, generally a better price/quality ratio than the competitors, in most cases, the ET91 being a notable exception.