While I only change eReaders once every 15 years or so, my choice does affect which read later service I use.
I got annoyed at Pocket (or rather Mozilla) making me use a Firefox account, and when I did connect the two, it got into a right mess as it turns out I already had a pre-Mozilla era Pocket account under the same email as my Mozilla account. So I imported my bookmarks into Instapaper and installed its Firefox plugin.
Instapaper is better: it renders more articles more accurately, it can import several thousand bookmarks without breaking and it’s not tied to a bigger company which could shutter it. There’s no social element to Instapaper, no algortihmic suggestions. But Kobos only work with Pocket, and it is always better reading from an e-ink screen than a laptop, tablet or phone. So it’s back to Pocket. Annoying, really. eReaders are such closed systems.