I've ridden loads of electric bikes, and I can say that there's not one that I'd have been unhappy with if it was the only one I could have.. It's only when you have specific requirements that it becomes easier to choose - like if you only have one leg, you need a throttle; if you're heavy, unfit and have hills to climb, then you want one with a strong motor; if you have to go a long way, then you need one with a a big battery; etc.
I've never noticed the difference in weight of electric bikes when riding them, but you do notice the difference in motor power. The other thing that is very important, but nobody ever seems to mention it, though fairly simple to change on some bikes, is the gearing. It's a real nuisance when you can't pedal faster than 16mph because the gearing's too low. You never figure that out on a test drive, but you do soon after you bought it. Full suspension bikes give more comfort, but carrying stuff is not so easy. I see people stuck on whether to get a bike with a torque sensor or a pedal speed sensor, but that's just plain nuts.
Most people are happy with the bike they bought unless it breaks down, and they chose that one because the bloke in the shop said it was good. If you're the type that spends a lot of time choosing/evaluating, then you'll probably always be wondering whether you should have got a different one - like when you're in a restaurant with a big party, and you look at what other people got, which often looks better than what you got. Another general rule: If the bike has regen, make sure that you get to try it down a big hill to check that it rolls avove 18mph. You get so little from regen, that to me, it has more disadvantages than advantages. Despite what the Neo's blurb and salesmen say, it doesn't have regen.
To summarise: All the different systems and components have advantages and disadvantages. When you add them up, they tend to equalise. All e-bikes are adequate, so, unless you have specific needs, buy one that you like the look of.
