Blue checkmarks are meaningless because Twitter is awarding gold and gray checkmarks. Soon, in my opinion, a different colored checkmark will be awarded to celebrities, CEOs, and mostly white men.
I was accepted for Post but cannot find an app on Amazon for it.
From my few weeks' limited use of Post, Tribel, and Counter Social, I agree with your descriptions. I'd like to like Counter Social but navigating it doesn't seem intuitive - I've actually printed out its manual (and keep putting off reading) - an indication of how much it doesn't just make sense to me. Tribel & Post seem easy and are organized (at least visually) very similarly to TW so they feel comfortable not challenging. I'm impressed with Post's care & feeding of its users. Tribel has a sort of post/meme creator feature that's nice. Of course none of them has the great access (via accounts & handles) to all public people and entities, the most valuable & irreplaceable aspect of Twitter.