Hi, I guess the first question is how well you could handle the ride if you didn't have an electric bike? If you mostly need the ebike to get up the hills, ride into the wind, a 500 watt hub motor should be fine, and batteries will not be much of an issue.
A lot depends on how much you want to spend. Right now there are good choices in many price categories. The cheap stuff is more proven because it comes out of China where they make the components in the millions. But the quality control is lower, and they aren't aiming for super high reliability. Some people ride ebikes very hard, mostly off road. That's a different set of standards.
If you are riding 15 miles a day on good or decent road surfaces, that should be normal duty expected of any electric bike. The motors are generally reliable. A lot of this stuff is proven simply because there are something like 100 million ebikes in China, and that is where parts are sourced.
You are most likely to have flats, something simple like that. That can be pretty frustrating. There are options if your paths are prone to puncture causing things. But you might practice changing the tubes, and carry a spare and a patch kit. In many ways, an ebike is a bike. Adjustments can be simple. There are tons of videos on YouTube. Clean and lubricate the chain. Check the condition of brakes. My manual has a checklist. Be smart about torque with the things you tighten.
It's nice to buy from a local dealer for warranty work and adjustments. It's helpful to rent a bike to see if it really works for what you want. Make sure you like how the bike fits you, how the controls are laid out. Good luck. They sell ebikes when people take test rides or rent them.
