What is best really depends on your needs and the style of ebike you are after. If it's an ultra-light portable ebike you need, you can't go past the ADO Air Carbon at just 12.5kg (with battery removed). If you need to carry gear then its big brother the ADO Air 20 Pro or Ultra is a fantastic, low maintenance option at about 19kg.
Orbea has an excellent range of lighter than usual ebikes, with some incredible bikes across all categories. The new Orbea Denna gravel ebikes are very light - approx 14-15kg (less if you choose the higher end carbon models) and they are powered by motors that you can tune to full power if you wish.
Orbea shine on the electric mountain bike front too with the Orbea Rise, also equipped with the same drive system as the Denna, that has the full power motor option. These range from just 16kg to about 18.5kg, depending on the model. Last but not least is the full power Kemen range. Fully equipped and around 22/23kg and with long range batteries.
If you want a full sized, fully equipped leisure and commuter ebike then its hard to go past the Kalkhoff L.B range, all between 20-23kg with rear rack, mudguards kickstand, lights etc included. If it is a lightweight belt drive that you want then check out the Kalkhoff Image L.B Advance .