Never trust vendor "testimonials" , opinions have to come from real everyday users of any kit or ebike who has no connection whatsover with USA/cANADIAN vendor or Chinese manufacturer.
THERE ARE TWO KIND OF BICYCLES; MADE IN cHINA AND NON-MADE IN cHINA.
I really never understood why people would think $500-600 el. bike kit put on say $500 bike frame would make reliable commuter to work everyday of summer say 200 days a year.
Even traditional good quality bicycle easly can cost $1000, I mean build from first class components.
Wen you add electric partrs it must cost more than $1500.

ULTIMATELY IT DEPENDS WHAT DO YOU NEED EBIKE FOR!!
For occasional pleasure trips in the summer only or do you need ebike for everyday commuting**********
BIG QUESTION..
You cannot make a choice of ebike before answering this question.
If you need reliable transportation and WANT your hands keep clean from constant tightening, udjusting, etc. you need serious kit like E+ or Tidal fORCE, FOR SURTE KIT WHICH COSTS MUCH MORE THAN JUST$500.
I am not connected to them in any way all I know E+ is made in USA and it makes tremandous difference in quality. 2500dol for 750W kit is not too much if you consider how durable and well built it is.
You will get back this 2500dol as gasoline savings in no time.
MC