If you have hills, I highly recommend a dual motor scooter. If you have crap roads, then you will want dual suspension, but that will increase the cost. Solid tires will be ok if the entire commute is newly paved path. Even those little lines in the sidewalk can be felt with solid tires.
To be honest, 3 miles commute while standing will get tiring.
If you choose a bike, then most 750w bikes would work. With a bike, it is very important to choose a bike that fits your body type.
Now is a good time to by with all the sales. Are you a handy person? You can save money going with a direct 2 consumer ebike. Ride1up has good bikes at a good price. Just know that with a direct 2 consumer ebike, you will eventually need repair or maintenance. Not many bike shops will work on a bike they don’t sell.