Regardless of if you're looking for a case for your original Switch, Switch OLED, or Switch Lite, PowerA's Protective Case is a great pick. They come in various Nintendo designs and offer all the features you need.
While it doesn't offer the prettiest design, this Nintendo Switch bag does have ample room for you to tote your Switch and a few accessories while everything is slung over your shoulder.
Since the Nintendo Switch OLED is slightly larger than the original Switch, the new console needs a specific case that's designed for it. Tomtoc's option is the slimmest one you'll find while still offering plenty of protection.