I am currently in the parts purchase phase for my second corexy (with my own design). Je vais utiliser une Duet Wifi paired with a Duex5 pour la controler. It will look very much like the E3D tool changer. It will have 2 hotends, 1 laser, 1 plotter (1 motor to lock the tool) and dual independent Z axis motor. My printer has a 500²mm frame with 400² motion limit (used with the laser) and a 300² heatbed. After reading the article about choosing stepper motors, I came to this result :

For the X/Y motion :
17HS16-2004S1 : 1.8° - 2.6mH - 2A - 45Ncm https://fr.aliexpress.com/item/32855316300.html
I don't think that the big brothers 17HS19-2004S2 with 59Ncm would be better ? Am I right ? https://fr.aliexpress.com/item/32994293330.html

For the Z axis and extruders, I was wondering if 0.9° steppers would be better. Because the Z axis/extruder speed are not really high, the motors would have more torque with the same angle lack and thus would be more precise ?

Do you have any other recommendation ?

Thanks in advance,
Arnaud