The following is true for either jet:

My .02 Cents, one of the few times I'll be on-topic: If you commute, the smallest bag you can get away with that fits a standard 17" laptop.
Having at least one bag that fits under an RJ seat is a huge help.

All you're required to carry by the company is your flashlight, batteries, the laptop and charger, and spare corrective lenses if you need them. The company will provide a pubs bag for the laptop. When mine wore out after 5 years, I bought a smaller one at Staples that was TSA-friendly. I find it much easier to unzip the bag-halfs rather than pull out the computer at checkpoints. YMMV.

Also, after having some friends forget this lesson from the regionals: Always, always, always bring a toothbrush and something to wear in the bar for when your easy EWR turn cancels in EWR because the good jet you flew in goes down hard on the turn... This WILL happen on both fleets, but quite a bit more on the 190.