Can someone recommend a good charger for 21700 cells please?

[Banjostring]

You won't regret buying an xtar I have the xtar vc4 had it well over 4 years & it's the 2 outer slots for charging the 21700.

Same as that Mutley, I've had my VC4 for almost 5 years now and use it pretty much at least once every day. I've never had a problem with it apart from when the charge rate occasionally drops to 0.5A, which is easily remedied with a quick clean of the contacts.