Bikes and batteries are mature in development and most are reliable. Your choice should depend on anticipated use and finance considerations. I have a direct drive DIY system that has operated perfectly as an errand bike for five years with the same 52V, 10 ah battery that has powered a BBS02 off road bike for the same interval. My daughter just told me of a fun ride she had yesterday with a six year old Dillenger system on her cruiser. Decide what you need and how much you can spend and we can help select the optimum system (look at today's post in the "battery" section" of an inexpensive kit in its sixth or whatever year).