Just about any bike will work for you, which makes it virtually impossible to recommend one. In that price range, the Oxygen S-cross MTB is very popular. I guess that it's because it can be derestricted to go pretty fast. If that's not important to you, then any bike would be OK. Take your pick. every different one has its own advantages and disadvantages.
If you're good with the spanners, there's some nice ones on Ebay. I wouldn't say that they're any more or less reliable than anything else, but if something does go wrong, you'll have to sort it yourself. If you're ham-fisted and non-technical, you need to buy from a local dealer to get things sorted. Halfords have some reasonable bikes and the prices are not bad if you use all the discount schemes, and they normally give big discounts themselves on bank holiday weekends.
Just about all electric bikes have something that needs sorting soon after you buy them - mainly small problems that you can fix yourself if you know how. Big problems are not very common on any bike, but they do happen.
The only bike I would avoid at the moment is any one with the Kalkhoff Impulse motor in it. They seem to have a lot of reliability issues. definitely don't buy a used one.
If you choose a bike, we can probably advise you on its strong and weak points - if it has any.
The cheapest bikes work and are most likely adequate for what you need. Like many things, spending more money follows a rule of diminishing returns. If you have money to spare, you can get a better bike, but it would be hard to justify spending more money on the basis of needs or costs.