I was changing my settings throughout the ride as I found that - especially on trail mode, it was too much assist and on some occasions I felt that the bike was driving me along and not the other way around.. in fact, because ive always used clipless pedals and race shoes but converted to flats for this bike, i found that the impetus of the bike was catching me out and I would lose a foot from the pedal pretty frequently.
from memory:
ECO: 25-45
Trail: 45-80
Turbo: 100-100
If I feel like I want to "work hard" - trail around 45-80 and eco 25-45 both end up "feeling" too easy so I drop them back. The reality I'm finding though is that I end up working just as hard no matter how they're set I just end up going faster when it's on the higher settings. Though to stretch out battery life, drop the second figure to be more inline with the first figure, otherwise as you pedal harder, the assistance amount increases considerably and so does power usage.