jlaw

Congrats on your decision - ebikes are great way to get out and enjoy the world even if your body is not 100% cooperative.

Get a name-brand bike (Trek, Giant, Specialized, Raleigh, etc.) with a name-brand mid-mount motor (Bosch, Brose, Yamaha) and a front fork shock from a local dealer who will be around in the future if you have problems. You have a good budget - too many choices to list - buy a bike that you can take for a substantial test ride and get a proper bike fitting.

Fenders, a rack, lights, etc. will make the bike more useful to you so you might ride more - for non-recreation - errands, etc. The bikes are speed-limited (mostly) to 20 or 28 mph. If 20 mph is good enough you'll save some money and you might get better mileage per battery charge because the motor is smaller and more efficient.

The front shock will help with your back. You can also add an after-market seat post shock like the Cane Creek Thud Buster - pricey but effective.

https://www.canecreek.com/products/seatposts/

Check out the reviews of the various ebikes at:

https://electricbikereview.com/category/bikes/page/3/

Once you find a bike locally that you like, check back here for opinions.

Also, don't expect an ebike to have the same trouble-free, long life that you can usually get from a regular bike. The batteries, controllers, and motors, are complex and have a finite service life - that's the reason to buy locally from a shop who can do diagnosis and repair. Ask them about the actual anticipated life span of the various components.

Good Luck.