What is the best workflow between Premiere Pro and AE for these kind of text-based videos?

When you are trying to do anything like this in After Effects it is incredibly inefficient to try and edit the entire project in one comp. Break the audio track up into smaller sections, a single sentence or even a phrase, and make each one of those a separate comp. You end up with a few layers in each comp instead of hundreds. Render each comp and then do the final edit in Premiere Pro.

This requires that you visualize the cuts and transitions and plan for them, and it sounds like more work, but it is way more efficient, makes changes a lot easier, and trust me, if you want to do a good job, you'll need a lot of changes.

Develop your own library of standard moves. I have more than 200 expressions that I have saved as animation presets that help with this kind of thing. They are all based on in and out points of layers, not on keyframes. If I have a text layer that I want to fly in from the left, bounce to a stop, then fall off the screen I just position the layer where I want it to land and apply this animation preset:

Dropbox - flyInBounceDropOut.ffx​

I get sliders and checkboxes to control the timing and it takes about 10 seconds to get the move I want by simply adjusting the in and out points of the layer.  If you are not good with expressions or do not have the budget to buy some scripts to help with that at least save moves you animate by hand as presets so you can apply them to other layers. There are so many identical moves in the samples you provided that a small handful of animation presets could be used for both the text and the images and that would save a bunch of time. Visualizing what you want to do with each sentence or phrase or sentence and breaking the project up into comps that are only 10 to 15 seconds long would save you a bunch of time in the long run.

I hope this helps.

Look into using Motion Graphics templates. They are for this exact sort of thing. Basically, you set up your animation in AE. Then you can reuse that animation as many times as you want in Premiere customizing each instance of it all within Premiere Pro. It's great!

User posed the same question on the Premiere Pro forum and got pretty much the same answer. Personally, I create all my mogrts in Premiere Pro so I can use them in Rush, which I really like now.

Some of these videos have quite a bit of speed changes going on. You can do those either in Premiere Pro or After Effects. Text would have to be done in After Effects or you can use this plug-in: broadcastGEMs typeGEMs 2 [Purchase] - Toolfarm in Premiere Pro.

Hopefully, we'll hear back from the OP.

Cheers,
Kevin