While our Karma's can only charge at 3.3Kw, and therefore only need a 16A charger, I strongly recommend you get a 30A or 40A charger at a minimum to future-proof yourself somewhat or in case any other EV may need to charge there. The higher amp models work just fine for the Karma but can charge other EVs much more quickly (the Karma too if you opt for PowerSources charging mod). I have two EVSE's, the original 16A Fisker-branded Lear and a Clipper Creek HCS-40. I'm a big fan of the CC. It's bulletproof.
Brent