Is it worth it to buy a 3DS or a Switch Lite? I'm thinking of having one, and buying the Switch is more of a future-proof gadget than N3DS. What are your thoughts about this?
I'd recommend you borrow a Switch from your friend for a while. Play Super Mario Odyssey or BOTW and then you can decide whether you want a Switch. Most of us buy Switch for games like that.
As for 3DS, it is dead. Big titles have released or will release their successor on switch. However if you want to play Pokémon, go for a 3DS as their Switch version is really disappointing, and I assume they will keep disappointing.
If you are interested in hacking it, definitely a 3DS. It's simple to do in any model and it has a ton of homebrew software. It's doable in the switch but you'd want a unit manufactured before circa Jun 2018 for now, the process is more convoluted and less popular.
Personall, the switch is too large for me to want to use it as a portable game player regularly, and the lite doesn't work with a TV, so I didn't consider it. Also, loading times for the Switch seem longer than my DS/2DS, but I haven't measured.
The 3ds line has a large library of fun games, but won't be getting many more at this point. I went with the 'new 2ds', because I don't care about 3d, but I like the clamshell, even if it probably means the hinge will break eventually, like on my DS; the original 2DS just seems unweildy for me.
As for 3DS, it is dead. Big titles have released or will release their successor on switch. However if you want to play Pokémon, go for a 3DS as their Switch version is really disappointing, and I assume they will keep disappointing.