The Subox Mini-C kit is a great way to start vaping or upgrade over a 'pen style' eGo battery setup with great features like airflow control, removable batteries and a larger tank.
The Crown II from UWELL features a great vape experience across a wide range of power settings. Good construction, feature set and price (with low cost coils) and you have a great all around tank.
The follow up to the very popular TFV8 series. "The Cloud Beast" has insane flavor and can handle a wide variety of power inputs.