I tried few years ago, and it didn't fit my needs. Just tried again :

  - must sign up to use the application
  - impossible to select several items to mark them as read/unread (possible in Aggregator, and I can't live without it)
  - the grouping is based on the feeds (same as Aggregator), but I'm looking for label grouping ala Gmail
  - must pay for the search/label feature
  - in text only mode, the items are hard to read. I like Aggregator's way of seeing the source's favicon next to the items
  - ads

RSS is free open standard, it's not supposed to change and does not require maintenance. Aggregator's last update was almost 3 years ago and the app still fully works as intended today. I'm not looking for an app that is updated every week for new features.

I tried all the free Android RSS readers under the sun, and none has the perfect combo of features I would like.