All the bikes you mention will do the job, but it is possible as others have shown to spend quite a bit less.
The Specialized has a spec that would do very well for moderate offroading - four piston brake calipers, 12 speed wide range gears - which a London commute does not need. And mudguards that offroaders would not normally bother with, but very useful on a commuter. You probably do need a rack.
It is the 'proprietary' type of bike that is often warned about as expensive to fix if it goes wrong. True, but how often do they go wrong, and why? Not often, and usually from hard use or excessive exposure to water.
It is also a 'mid-drive', with the motor driving through the chain and gears. Together with the torque sensor as the means of control, this gives a very natural cycling feel when you ride it. But do you need that for a commute? If you want the feeling of bionic legs and lost youth, then yes. If getting from a to b effectively is more important then you can live without it.
The Engwe E28 is expensive for a rear hub motor bike, but the belt drive makes it clean and easy to live with, and if reliable enough, the two speed hub is probably all the gears your commute needs.
The E26 is nothing special, and rather heavy, so I would look at alternatives to that. The Woosh suggestions above perhaps.
One or two final thoughts: 20 miles a day is substantial: quite a workload for both bike and rider. 5,000 miles a year? I'd just do a 'sense check' before committing to an expensive bike, although the likely cost savings against other means of transport probably mean there is not much to worry about even if you don't ride every day.
My 3.5 year old Shimano mid-drive has clocked up 20,000 miles. It might manage the same again, might not. You might end up writing off the cost of the bike over two or three years. Does that level of depreciation look OK?
Many commuters use folding small wheel bikes to keep the flexibility of trains without special bookings. Do you need that possibility?