I think hub motors are better. People sometimes have trouble with the installations of those chain driven motors. Sometimes they'll even bend their frames getting those chain driven motors installed. Also, with hub motors, you don't have to worry about the chain breaking or the motor overheating. Chain driven motors require a specific RPM in order to function properly and if it's not within a certain RPM range, then you'll overheat and destroy the motor. So people often have to route the chain over a few more pulleys or whatever they are called in order to get proper RPM.
ampedbikes.com
ebikes.ca
e-bikekit.com
hightekbikes.com
itselectric.ca
Those are the well known and reputable ones. I think any kit that has a nine continent motor is pretty good. Those being the ones offered by ampedbikes.com and e-bikekit.com and also ebikes.ca sells them too. Hightekbikes.com sells a aotema motor. It's pretty good also and they say goes a little faster than the nine continent. The nine continent is probably better made, though. Itselectric.ca has all the little accessories that are hard to find elsewhere like battery cases and stuff. They have both a U.S. and Canadian store. A lot of people like ampedbikes.com .
For battery, most anything except SLA's are good. Ebikes.ca has some cheap NICD batteries but their lithium prices are too expensive and you can find a better deal elsewhere. Elitepowersolutions.com is a good place to find decent lifepo4 (lithium) batteries for relatively cheap. They don't sell BMS's though so if you went with them, you'll need a cell log monitor from hobbyking.com ..they are only $15, though. You'll need two, though. It's called a Cell log 8s monitor. Lifepo4 cell range has to be from 2.5v - 4.2v and if you go below 2.5v or over 4.2v, you'll destroy them. Other good places for batteries are:
evcomponents.com
pingbattery.com
And that's probably about it. I can't recommend any ebay batteries or ebay anything for that matter.