An interesting thing, to me at least, is that I've never driven a manual car (manual tractors yes).
I wonder if I have an unusual use case for an ebike in that I want to bike for exercise but would like the ability to be slightly faster and able to climb steeper or longer hills. I'm looking for an ebike that is as close as possible to a standard pedal bike because I do like responding to differing conditions through changing my pedaling and changing gears.
One system I haven't mentioned in this thread is that I almost like the Kepler friction drive mentioned on this site for being light and possibly able to be set up to only be engaged when you need it. That way I could have a small battery pack (light) and only engage the friction drive when I wanted to power up a hill but otherwise treat the bike as a standard bike. If only it didn't rub on the tire!
I have about a half dozen e-bikes at this point, and have sold about that many more. Bout half and half factory e-bike bought used, and half conversions I did, a mix of hub motors and mid drives. (I'm a fairly fit 69 years old)
Off all the bikes I've owned, the torque sensing mid drives with IGHs are the ones I like the best, they have the most "bionic legs/fountain of youth" feel to them. With a single speed quality chain, drive train maintenance is almost nonexistent (unless you put thousands of miles on them in a year)
A couple of my mid drives use the TSDZ2B, and I'm happy with them. I wouldn't recommend them if you jump, or stomp on your pedals, or want to go 35mph for extended periods, but otherwise, they seem fine, and offer a very transparent riding experience. One of those uses Ryobi yard tool batteries, which lets me take along just enough power for the ride planned, and hot swap charged batteries as needed. That bike is an old steel frame full suspension mountain bike, and the whole bike, complete, has less than $800 in it. It wouldn't make sense if you had to buy the ryobi batteries and charger, but if you already have cordless yard tools, it's a cheap option. You could probably find an old TREK steel frame MTB that would accept the Tongsheng mid drive easily, and get it on the road for $500, but....
Right now, used E-bikes are selling really cheap (though the really good old mid drive 24v ebikes from the 2000's seem to have all been scrapped) If you can wait until fall and keep an eye on craiglist, you can find legacy brand E-bikes in good shape for $750 or under. I just bought a cannondale neo allroad speed, that sold for over two grand, only two years old, for $500. It's seen hard use, paint chips and needed a good cleaning and tuneup, but it's the top of the line, 750 watt front suspension bike on 26"x2.6" tires. It has cadence sensing, but a pretty good version of that system. I wouldn't buy anything too old that uses proprietary systems...no Bionex, no old Chinese folders, or fat tire anything.