We have one of each. My wife has the 2018 Evelo Aurora step thru cadence sensing 750 watt Enviolo automatic. I have a 2018 Biktrix Stunner Step Over with a cadence sensing 750 watt and the Shimano 5 speed e bike rated IGH. My bike came with the 5 speed Sturmey Archer and assurances from Biktrix that it would be strong enough. It started to crater right away and degraded this year to the point that I replaced it. Biktrix still sells my model. They refuse to acknowledge that the Sturmey Archer IGH on Stunners are not only inadequate, but that Sturmey Archer waves people off of it for mid drive apps. DON'T BUY A BIKTRIX.
All that being said, I'm slightly bent towards the Enviolo. Our mileages are almost identical, with her 672 watt*hour battery, and my 25% larger, 840 watt*hour battery. I don't think that my greater weight changes things that much. Put directly, even though we can feel drag on her bike when the power is off and no drag on mine while the power is off, I don't think that the Enviolo trans fluid costs her much power and range..
Also, she has more low end pull, since the ~2.6 spread of my 5 speed, while fine, is less than her ~3.8 - both with about the same top speed. We can both pull our Bob trailer full of groceries or adult bevs, up and down San Francisco hills.
My Shimano is new and I expect good service from it. But my wife's Enviolo is already proven. Thousands of miles.
The worst problem she had was only Enviolo "adjacent". She had a temporary (presumably) high temp motor shut down while climbing the long, steep hill on the Pebble Beach 17 mile drive. Her pedal cadence was set near minimum, and we suppose that the combination of low motor speed and heavy load got to it.. Since then she has learned to twist it up higher on hilly terrain (her setup has this on the handlebar, but newer installs might have jetted it), and her Enviolo has done well ever since.
Two last points.
1. Do the input torque arithmetic on whatever you buy. My Shimano e bike rated 5 speed IGH can handle 85 n*m, and I can supply 80 with my motor and my combination of pedal and wheel sprockets.* Close, but since I seldom use more than assist position 2 (of 5), and experimentation with the higher assist levels shows them to be much more torquey, I think I'll be ok.
2. If you want oil change capability for a Shimano e bike rated IGH, without pulling the hub apart, I think that is offered with more expensive, higher number of ratios, models. I will have to pull mine off when the time comes, but I think I can do so carefully and properly. Even though I have yet to find a youtube on how to do so with this specific hub....
*Yes, pedal power adds to this. I'm still confident.