What stepper motor to look for?

Other Hardware Motors, Mechanics, Power and CNC
1

I need to buy a fairly small stepper for my magnetic stir plate. I need about 500rpm maximum speed. Should I go for:

1
Step Angle: 0.9 degree
Voltage: 1.92V
Current: 2.4 A/phase
Resistance: 0.8Ohm/phase
Inductance: 1.8mH/phase

or

2
Step Angle: 0.9 degree
Voltage: 2.8V
Current: 1.7 A/phase
Resistance: 1.65Ohm/phase
Inductance: 4.0mH/phase

I will use a driver with current control.

2

No, go for 1.8 deg/step, that immediately gives you twice the max speed
for any voltage/driver combination and a lower pulse-per-second
requirement.

Go for 1.7A and a DRV8825 driver which can just about cope with that
current. Then I think you have a reasonable chance of a stable 500 rpm
from 12V, or if not then 24V.

Try the different microstepping options, with a plate to drive the inertia
may mean that even full-steps will be free of resonance. AccelStepper
library allows ramping (almost certainly necessary) but has a rather
low max step rate, so half or full steps might be needed.