Love my New 2DS XL with cfw, but the best form factor for me for those you mentioned is the Miyoo Mini.
I have it in my pocket all the time and put has save states, fast forward and low power standby with instant power on.
I can play it in short busts whenever I have a few minutes spare instead of using my phone.
I recently beat Pokémon Emerald for the first time thanks to this and I'm further through dk county than I've ever been