My problem with Thunderbird (and the reason I switched to NewsBlur, which I happily pay for, although there's a freemium tier and you can also run it yourself) is that it has to be up to receive updates. That may be acceptable on an always-on-always-connected desktop, but on a laptop, when traveling or when I occasionally take a few days off technology - it means thunderbird has likely lost updates (most RSS feeds only publish the most recent 10-20 stories, so you need to poll them frequently).

Not affiliated with NewsBlur other than a happy customer of 5 years, highly recommend it.

+1 Thunderbird, however I also use it for handling a collection of IMAP inboxes and importing iCal events.

I only use it for email.