Nano's are what I normally use but because they come from OS, there is usually a two week delivery delay.
I've been using the locally available Turnigy 30C's for experimenting with different sizes since they are cheap and in my letterbox within 3 days.
I actually had my first Turnigy battery failure yesterday when a track on the battery circuit board melted/cracked, causing my Plasma to lose all power and land ungracefully into the swamp! Fortunately no damaged and I've repaired the battery by soldering on a copper wire "jumper".
The weather looks good today so off to do some more "testing" right now!