You can get a
very light variant of the
Ribble Endurance SL e - 10.5kg. However, you'll also get a very light wallet!
The Boardmans and the basic Ribbles/Orbeas (which are all roughly in the 15Kg area) seem to be a good balance on the weight / price trade-off if you're after some assistance as opposed to shedloads of assistance.
However (as stated by other posters above) if you need LOTS of power, then you'll need to go for something heavier. Big batteries weigh a lot, and need a pretty solid frame and space to mount them onto.
In terms of looks, the
Ribble & Orbea Gain/Vibe are tidier with a smaller diameter down tube than the Fazua. However, that comes at the expense of no removable battery, which in turn may be good - in terms of possible battery theft*, or bad - in terms of having to bring it into the house to charge it if you have a bare garage like mine.
*Ribbles & Orbeas don't even look like eBikes - another possible bonus on the theft front.