What to choose

[Nealh]

Hub motors very rarely go wrong and can be self repaired, there isn't much to go wrong unless fitted in the drop outs incorrectly.

 

[KirstinS]

and the point is what

Only that it was not what was actually asked SW.
He didn't ask for speed or a lesson on the law. Just to be sweat free for work

A fast, dongled bosch is not the answer for that requirement in my view. Hence the cadence vs torque sensor info I wanted to give.

You also have assumed what my views on illegal bikes are. I have never said a word on the subject other than let people know the score to make their own minds up.

For the OP, try a rear hub cadence sensor bike

 

[Amoto65]

While singing the praises of the Carrera Crossfuse I also have a Wisper 905se which is a cadence rear hub and this has also been excellent over the last 2 years and 2000 miles once again going all over the Peak District, my suggestion is you go into somewhere you can test ride both types of motors and see which you prefer.