We have a Boardman and an Orbea (ebikemotion system like the
Ribble). Both work on the flat too - not just up hills.
The Boardman is well made, the battery+motor is removable, and with the battery removed it's not noticeably heavier than your average bike - maybe an extra 1kg. Adding the battery+motor is noticeable if you're lifting up at an awkward angle or away from the body (force * distance and all that) so into a car, onto a roofrack, etc needs care and some strength. However, up stairs the lifting should be quite straightforward.
The ebikemotion-based bikes (Ribble, Orbea, Lapierre, etc) are also good quality, and slightly lighter (maybe 1kg less without spending a fortune on carbon), but you can't remove the battery.
The only word of caution against both of these is if your ride has properly steep hills (1-in-8 or steeper) then you'll still need to put a significant effort in = likely knee pain. I believe the Bosch-based bikes will work better up steep hills (more peak power?).
I haven't tried a Swytch, but for casual cycling, it looks like a simple and affordable system, with the limitation being the front wheel drive and the front-loaded weight (both battery and motor).
In terms of outlay you're paying something like £1200 extra over an equivalent non-ebike for the Boardman, Bosch & ebikemotion bikes - but you are getting a whole new bike of course. Selling your existing bike can soften the blow a little.
I wouldn't pay £1000 for the Swytch - that's just a headline price, not a realistic one, but £500 is tempting if you're not in a rush, especially if you're happy with your existing bike.
[Edit: I should say, both the Boardman and ebikemotion are game changers in terms of enjoying riding again, even though some people rubbish them for being lower power motors with smaller batteries. They give enough power in most situations, and plenty enough for 20 miles even at full power, which I doubt you'll need.]
.
