The Switch is the new latest and greatest and if you can get anyone you want, that's the one I'd suggest. If is BOTH a home console where you can play on the TV and a handle console that you can play on the go. Yes, it is that slick and works perfectly switching between TV and handheld modes. It's going to play all of the latest games like Zelda: Breath of the Wild and Super Mario Odyssey; plus tons of indies and other non-Nintendo published AAA games. The Switch is really the way to go if you don't have anything and are getting one.
The 3DS and 2DS are similar is many ways. They play the same games. They also play the old DS games. The biggest difference is that the 3DS can do both 3D and 2D, you pick. The 2DS can only do 2D. I have a 3DS, but personally never use the 3D. And up until recently, only the 3DS could fold and close making it easier to put it in your pocket. But now there is a new 2DS version that folds as well. There are a lot of great titles on the 3DS/2DS. But there won't be a lot of new titles coming since the Switch is out and that is where Nintendo is focusing it's attention.
But all three of those options are great. It's really where do you want to focus.