Then from my own personal experience if you can't have a very high watt and amp hub motor set up,
( People who are under the many draconian EU Rules ) then a Mid-Drive system is best.
Next thing is for you to experiment with different front chainrings .
If you do get the cheap chainring adaptors from AliExpress , be sure to several chainring spacers for the BBSxx series motors
Different bolt pattern for the BBS02 from the BBSHD .
The cheap chainring adaptors were designed in such a way that when you bolt your chainring to it the bolts rub on
the Housing of the BBS02/HD making a awfull sound and scraping up the Housing . The Chainring adaptor spacers
will avoid that by spacing the adaptor out a little . However that also puts your chain line out more .
If you have the money better to get the $ 30- $ 40 Machined Chainring adaptors , I have both that is how I found out the
hard way about the cheep ones.
It is always helpful to have some adaptor/chainring spacers around just in case you need them .