I used to use the Vivi Nova tanks, and liked them when they were working well. But sometimes they have problems delivering enough juice, which sounds like the issue you are having.
Like you, I don't want to "fiddle", I don't want to roll my own coils, I don't want to change the wick, etc.
I moved to a Kanger Protank II with one of their airflow control valves, and I've been happier with it. It has wick/coil on the bottom, instead of the top, and I think that helps a lot. Also, when I used the ViVi Nova, my juice would gradually get thick and dark and I'd eventually have to dump some of it and start over. With the Protank II, that never happens.
Like you, I don't want to "fiddle", I don't want to roll my own coils, I don't want to change the wick, etc.
I moved to a Kanger Protank II with one of their airflow control valves, and I've been happier with it. It has wick/coil on the bottom, instead of the top, and I think that helps a lot. Also, when I used the ViVi Nova, my juice would gradually get thick and dark and I'd eventually have to dump some of it and start over. With the Protank II, that never happens.