Welcome! You are in the right place.
The research part is time consuming, but I think there's nothing for it but to just keep exploring. Start with Indianjo's suggestion, and then head over to the review section, read, watch, and compare specs.
It is true that you learn more in the saddle than you can on paper, but it's hard to find bikes to test ride, and the other problem is that test rides can be deceiving. I actually considered returning my bike after I bought it, and now you'd have to pry the bars out of my cold, stiff fingers.
And honestly, I'm not completely sure why that is-- part of it is that I learned to ride a mid-drive and my shifting technique improved, part of it was that I did some mods, part of it was that I was in much better shape physically after riding it for 200 miles, and part of it seems to be that the motor did seam to need breaking in-- though that's not a thing, I'm very new to this, and the only person I've heard of who ever reported that!
Some of the first questions to ask are:
* Class I, II, or III?
* Throttle or Pedelec cadence sensor / Pedelec torque sensor?
* Hub drive or mid-drive?
* On road or off?
* Where can you get service? Will your local bike shop work on your bike?
After making those decisions, I'd look at quality of parts, power, weight, battery capacity, etc. It's really messy, because so many of the decisions are interdependent. A 58 pound bike with a 500 W battery may the same range a 50 pound bike with a 400 W battery, and two 250 Watt mid-drives may have totally different torque ratings, one may be far more efficient than the other, etc.
These are strange beasts, particularly the mid-drives. If you want something with a lot of power that's more like a motorcycle, mid-drive may not be for you. I think they are great for fitness rides, but it's unnerving at first that the bike kind of "wants" you to pedal in a certain way so it-- and you-- can use your energy as efficiently as possible. It's kind of like riding a robot, which I found disconcerting at first-- but much less so when I learned the kind of hills it could climb, the terrain it could handle, and how stable it was going over 35 MPH (downhill.)