I don't know your budget, but one of my uncles has a Rad Power Bike and I rode it to and from the store while watching his house for a week and was pretty impressed by it (this experience may have directly lead to me buying a motorcycle last year). The link is to the currently-cheapest one on their online store, although the one I rode was one of their earlier models from 5ish years ago. Oh and if you get something like this don't get the official accessories - bike bags and baskets are a pretty well-trodden standard and you will almost certainly be able to get something cheaper.

edit: just saw that you weren't looking for a specific example, but things to look for. I would definitely check to make sure you'll be able to unlock the top speed before buying - some bikes will have an "offroad" mode that you can just switch to to unlock the real top speed, others will require some finangling. And if you bump it up to above 20 MPH remember to pair that with motorcycle-grade safety gear - you don't need full ce2 armor on everything but you'll need a real helmet and long pants/sleeves that can slide at a bear minimum.