[aziaziazi]

Internal gear hubs are pricy but great. I’ll strongly advise against a conventional derailleur with a mid-drive motor: the derailleur needs a thinner chain which wear faster, especially with a motor that apply more torque than a normal human. Internal hubs allow to use a 1s chain or better: a belt. Then you’re good to go for a loooong time. There’s also the (super expensive) Pignon mid drive with integrated speeds, a bit like the Schlumpf’s but for e-bikes.

Pro of derailleur’s e-bikes: their price.

[waited long time to do that] - a former bike mechanist

edit: the problem with faster wear isn’t the risk to break but the decease in efficiency which will affect your motor health (heating) and batterie capacity. If you’re on a budget there’s a compromise: find your favorite gear and replace the derailleur and cassette with a single speed front and back sprockets (and chain). Beware that might not be adapted to hilly roads as GP environment.

[loeg]

> thinner chain which wear faster

This gets repeated a lot, but isn't true. Cheaply made single-speed and 6/7/8 chains aren't any more robust than nice modern 10 and 11-speed chains. Shimano CUES (11-speed) works fine for ebikes.

Belts are fine, but less efficient than well-maintained chains. And they require special frames with some way of breaking the rear triangle.

[aziaziazi]

I wasn’t comparing 6/7/8 with 10 and 11 but with 1 speed. Those are indestructible. But as you noted the quality of the chain is also important.

As for the chain you might be right, but a well maintained chain over time needs more work that many wants to invests. It’s an option for the hobbiest and sportmans but not for most of daily commuters which want something that just work, days after days and years after years.

Also, e bike users tends to user the higher speed way more than others so that sprocket wear off faster than others, accelerating wear even more. I’ve replaced many cassettes with all the speeds almost brand new and the faster one totally destroyed.