Question Ranking
Pros
Pro Amazing customizations
You can personalize every aspect, from spacing to fonts, colour customization, lines, etc.
Pro Constant updates and responsive dev
Frequently updated to support Twitter's API and a dev that listens.
Pro Great material design, hover and animations
Cool animations, material design and the hover feature for profiles is especially helpful.
Pro Cool themes
A number of themes available with an import and export feature.
Pro Grouped replies
Connects replies in the timeline and per tweet, good for following threads and conversations between users.
Pro Link preview and reader mode
Preview of shared link's site address, title and header image directly in the timeline just like official app. Reader mode extract shared article content for quick unobstructed reading.
Pro Multiple app drawer icons available
If you don't like the main Flamingo icon, you can choose from a list of app icon options.
Pro Save tweets to read later
Temporarily save tweets in a separate tab for later viewing.
Pro Has push notifications
You can turn on push notifications as long as you have the official Twitter app on your phone.
Pro Android's first true Tweetbot alternative
For those that have been searching for a Tweetbot lookalike, a solution may have been found with Flamingo.
Pro You can add an activity tab
Shows all account activity - mentions, likes, retweets, etc in one column. You just need remember to add it in the layout option.
Cons
Con More widget options
Needs more widget options.
Con Better notifications
Needs better options for notifications. There is no real time notifications, but this is Twitter's API limitation.