Hello Anne
The best advice is to work out what style of bike you want, then what you actually need from the bike (road use, commuting, or hurtling up and down mountains). Your size and weight will help. How far you need to go (do you need powered support for five or 50 miles?). A general principle is if it's road and commuting work, a hub motor will, as a rule, suit you better. But if it's technical, off road mountain bikey stuff you're after, then a crank drive system is likely to be a better option.
Then go to some bike shops and try as many different bikes as you can, because it's only by actually sitting on them and trying them that you'll get a feel for what is right for you and what is not. In my experience, trying bikes I was not really interested in (taking my blinkers off) turned up a right couple of crackers I'd have otherwise missed.
The Orbea Keram has the Shimano STEPS E6010 system, which is the same as I have on my Whyte Coniston. That's plenty to get my 6'4" and 16 stone 40 miles, but other people say the Bosch drive motors pack a bit more punch.
There's a good value Cube here:
http://www.hargrovescycles.co.uk/cube-reaction-hybrid-hpa-pro-500-grey-red-2017-electric-bike.html?gclid=Cj0KCQjw9uHOBRDtARIsALtCa96OcDI0qMxY2yHcx2t1_iUOcCYtE0I44_WlkGdQ8qXFqVoTWOEU1oUaApVJEALw_wcB
Happy bike hunting!
Gaz