As one of the comments states, "best" is subjective. This is directly under someone recommending AquaMail. What works well for me may not work well for you.
I've been using AM since the Kostya days. It does what I need/want in an Android email app. I have no issues with Mobi trying to monitize the app as long as those who bought a "lifetime" license a while ago were grandfathered in. And they were. I agree that their forum presence could be greater, but then the overall traffic of the forum has dropped.
The bottom line here is if you don't like it, no one is forcing you to use it. And the "I paid for it I have to keep using it and they need to keep updating it" rant doesn't really fly. How many apps have you bought over the years for your phone? And how many have you grown out of? Or stopped using for one reason or another? You don't like it, move on.
