Either can work well. It's al about learning to run the one you've got properly. The pumps are usually a bit lighter. The autoloaders are usually a bit gentler to shoot.
Both of the guns you are trying to choose between have very good reputations. The 590 is a solid performer, and the 930 has a good reputation for reliability and as a soft shooter for a 12 Ga. autoloader.
So it comes down to which one do you prefer, and want to get good at running?
I've been a pump shotgun guy for a while, but I'm liking the Mossberg 930, the Remington 1100 and the Benelli M1.