You buy whatever bike you want that you can afford, with consideration of how it's going to get fixed when it goes wrong, which will happen sooner or later.
For road and trails, all electric bikes work pretty well. You don't need to spend anything like that money to get a nice bike that does the job really well.
It's an absolute fallacy that if you spend more money, you get a more reliable or more durable bike. I can guarantee that the opposite is true and that your running costs for an expensive bike will be more than they'd be for a cheap one - by a substantial amount.
Buy an expensive bike because you have money to waste. It's very easy to psych yourself up to spending more and more when you research that this bike has better gears and this one better forks, and so on. You don't need any of those things, and if you're truly pragmatic, they give you very little benefit when riding on the road. The only thing that really makes a difference is hydraulic brakes. The rest is just one-upmanship, and in many cases is detrimental to normal riding.
For riding on the road and trails, a hub motor has many advantages over a crank motor, so that's what I'd be looking at.
In summary, you cannot fix Bosch and Shimano systems yourself, so, if that's what you want, you have to buy from a local dealer. If you want to fix your bike yourself and be master of your own destiny, buy a bike with a Chinese electrical system.
General advice: Don't buy anything you can't afford, and never take a loan for anything. If, like me, you have thousands of pounds in the bank because you never wasted your money on things that you didn't need, you can buy whatever you want, but you'll probably have a bigger problem deciding what to spend it on because you realise that there's nothing you need.
