That sort of info should be in a sticky for those looking for info and just getting into the EBR world. It would have been helpful to me. If it is, and I missed it, apologies!
Being in the US, I don't have to worry so much with geo restrictions (didn't even know about them until recently). But choosing an EBR is a combination of knowing what sources you want to use for ebooks (how do you know that if you're new to the EBR world?) and finding an EBR that feels comfy to you. There again, until you have some experience in the EBR world, you likely won't know what features will be important.
I figure it's like most things in life. You buy the first one or two devices for the education and then you get the one you really want down the road a bit.