I've had both, but now have neither. I liked the P238 better because it was lighter and much easier to shoot. I only got rid of that one because I could not get ammo for it in the early 2010s. I wouldn't mind still having it. The P938 was a bit more harsh to shoot. I agree with the comments about the trigger. I did find it best to keep the rails well lubed on both and found that they would begin to malfunction if you shot 50 rounds through them without re-lubing. That made them too finicky by current standards but fine for self-defense guns.
I've had my 938 since April 2017 - I've put about 400 rounds through it without cleaning or lubing - finally, the last 50 rounds I had to push the slide occasionally to fully seat it due to it not coming forward to full lock during firing - due to accumulated dirt/carbon build-up.
That was planned, I wanted to see how finicky it was - not bad for a semi-auto (my Baby Eagle took over 1,000 rounds before showing the same symptoms).
Just after buying it I installed a pair of Hogue grips - the improvement was massive (aided by buying 3 of the extended magazines with the finger hook).