I've heard of people using 4 AA's, CR123's, and 18650's and I was looking for some advice on what batteries would be the best and how many would be needed.
P.S. I'm using an Aixiz 1 Watt driver
Depends on what fits your host, but if have the liberty of choice, 18650 are the way to go, unless you want to get fancy.
How many (1 or 2) depends on your particular driver input voltage requirements.