Which e-bike should I choose for city delivery?

For courier work, an e-bike is actually pretty practical. From what I see on the market, budget models with a motor on the front or rear wheel are popular - they're simple to maintain and quite reliable. If you're after maneuverability, smaller frames and 20-inch wheels are less of a headache - you'll squeeze through anywhere between cars. But the battery is the main thing for a full day of deliveries. Look at models with a capacity of 500 watt-hours or more, preferably 700+, then you'll get 60-80 km per charge under real city conditions.

As for specific brands, pretty much everyone has decent options at reasonable prices now. Xiaomi, Decathlon under their own label, local manufacturers - they all put out something that works. The key when choosing is to check the warranty and find a service center nearby, because sooner or later you'll need a battery replacement or motor maintenance. Test it before you buy if you can - ride it for at least a couple hours to see if the riding position is comfortable and how quickly the acceleration responds.

One more thing: go for a model with water resistance or at least splash protection if you're riding in the rain often. And don't forget about mud - mud kills the motor and chain, so a good kickstand and fenders save you money on repairs.