Much of the advice you get on forums is not in your interest. Most people are trying to justify their own choices by urging you to buy what they bought. Whatever you do, don't listen to anyone who tells you not to listen to the advice of others...Hah, I guess that eliminates me
The best thing you can do is be as precise as you can about how often and under what conditions you think you are going to ride. This will help a knowledgeable dealer guide you to a bike that will serve you best.
If you are like most of us you will ride your ebike more often and further than you ever imagined possible. Spending more money on a better built, safer, more reliable bike will be one of the best decisions you ever made. And I suspect I am not alone in that once I got going with my first ebike, I discovered latent capabilities within myself that lead down the road to longer. more athletic, endurance riding, something that never occurred to me going into it. Buying a better, more versatile bike at first kept me riding longer till I could afford the kind of bike that I eventually learned would be right for me. That process took over a year in.
Add a grain of salt to the advice you get here. Some of it can be quite good and well informed but there are occasionally shills hiding in the corners, promoting their new brand. And then there is the fact that individuals riders often exhibit confirmation bias in their comments just wanting to give them affirmation for their choices.
Do it your self/retrofit guys can't imagine why someone would spend good money on a manufactured bike from the ground up ebike. Fans of low priced, Chinese made, hub motor bikes would not be caught dead on center drive bikes. Fans of German made equipment really don;t hardly bother looking at bikes from other countries. Some people will never even look at a bike without a throttle, while other would never have a bike with one. fans of a particular brand will insist the one they chose is the only one to buy.
If you are like most riders, you are not a mechanic, don't have the know how, tools, time or interest in converting a bike to an ebike or maintaining your production bike. Some of us live for this stuff others just want to ride. Most will need help from a local bike shop. Don't expect people at that shop to care about keeping your bike running smoothly if you bought a bike on line.
The only support you will get from an on line seller, if you are lucky, is phone help to diagnose the problem and they send you parts to replace yourself or you will pay a local shop to replace for you.
If you decide that building out an ebike is not for you, it is likely best to spend a little more and have a dedicated local shop standing behind the sale in who's interest it is to keep you happy and rolling along.
The most common comment I have heard from new ebike owners is almost always something like: "I never imagined I would be riding a bike this often or this far" Buying a cheaper, mass produced bike may or may not give you the same quality of "whoopee!!" experience that boosts you right into an enthusiastic embrace of ebiking.
All too often people who buy lesser bikes seem to arrive at regrets sooner because the bike's inherent limitations just never quite enabled it to do what they want. Personally I ended up spending way more than I initially thought I would or should. Given how much time I now spend on my bike, something I never could have imagined, I am glad I spent what I did and got a bike I can count on, that enhances my enjoyment every time I ride it.
My advice: Make an honest assessment as to how you will be riding, road or trails, easy grades or mountain trails, commuting, exercise/fitness or touring. Take your time but don't get bogged down in research paralysis. Test ride lots of bikes until you find the one that puts the biggest grin on your face and the people selling it you like the best. Then, if you can possibly afford it, pay more than you first thought you were willing to spend. The pain of paying out some more money wears off quickly. The joy of riding a bike that really suits you will endure long into the future every time you saddle up.
