I'm doing exactly the same thing and I'd agree with everything you posted. I much prefer the setting of AC: Odyssey but RDR2 is just polished to a level way beyond AC that in nearly every objective way. The long load times, the semi-frequent bugs/slowdown and horse animation that looked fine in Origins that now looks clunky at best... they're all that bit more noticeable.
RDR2 was not perfect and Odyssey is still a great game, but you can really see where the extra time it took to develop RDR2 went.