Good question! It'd be fair to say that my knowledge doesn't stretch much further than "not Amazon". They do have some other nice features, though. For instance, they use the open epub format, and allow me to borrow books for free from my local library via Overdrive.
I would still say look into un-DRMing your collection and backing it up if you can, every chance Amazon will find ways to muck people around in the future with their copy protection stuff.
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I have been a kindle library lover since 2011