Google Reader. There are no replacements that a) update fast enough, and b) allow search for free. I know, I tried all of them. Firefox had an amazing plugin called "Ubiquity", which was basically like command line for your browser and you could write custom scripts for it. It was seriously better than anything that exists today. They stopped developing it for some reason. Tab Groups is another feature that's now aba…
How was Google Reader different than other feed readers such as the one built into Thunderbird? I didn't use it so I can't compare, but Thunderbird works well for me here. Side note: I also use it to subscribe to YouTube channels without a Google account.
Thunderbird requires that I have an application installed on the device.