My wife carries the Glock 43, I have the SIG 938. The SIG is slightly smaller, trigger is better, and with the Hogue rubber grips the felt recoil is slightly less than the G43. The SIG comes with night sights which I like. I only use the gun with an extended magazine because with the flush magazine the grip is just too small for my hands.
Malfunctions....the gun itself has never malfunctioned...but, if you grip the gun high on the frame, there is a possibility of inadvertently pushing in on the magazine release. The magazine will not drop out of the gun, but it drops down far enough that the gun will not pick up the next round and locks open. Meaning, you have to be careful with your grip on the gun.
My wife likes the G43 because it does not have a thumb safety and is a bit lighter than the SIG. She doesn't like the Glock trigger, but understands the stiff pull and longish travel required because of the safety mechanism.
I do not like the Glock specifically because of the trigger and sights which are just white dots. I know, you can "fix" the trigger by changing parts. It's a carry gun for my wife - I'm not going to do that. I also know I can change the sights, and will probably do that.
Have never held or shot the Ruger, therefore, I have no comments on it.
I'd suggest that everyone here will just tell you their personal preferences. There is no definitive answer, all three are very good carry guns.
You should choose the gun on your personal preferences. Obviously - size, weight, number of rounds, safety / no safety, trigger pull, number of rounds, and grip size are functional considerations.
You can't go wrong with any of the guns. Pick the one that fits your requirements and budget, and feels best in your hand.