I am a gadget collector! So I have in ereaders: Sony PRS-350, Nook ST, Kobo Glo, Kobo H2O, Kindle Paperwhite. In tablets: Fire HD7, Fire HD8, Fire HD8.9, Insignia 10". Love and use them all from time to time depending on need and circumstance. Why limit yourself, if you can afford this reading habit?? (I don't have many other vices and my obsession doesn't hurt anybody...)
May I suggest investing in a good powerbank which will charge all the above via USB. I just got a Portable Charger RAVPower 16750 on Prime Day for $22, regular price $32 (
link) which seems to hold a good charge and tops off all my devices nicely.