I'm not sure who everyone is, but the everyone you talked to apparently has no clue about this tank. Take everything they say with a grain of salt in the future and don't rely on their opinions. The full size Subtank has very good airflow, but not as good as tanks like the Billow or the Atlantis. It also doesn't do well at all at 30watts. A better wattage is 20 to 25. The flavor is very good and the vapor is also good, but not on par with the Billow or Atlantis. Vape it for a decent amount of vapor and flavor at 20 to 25 and it is very good, anything more than 25watts and it spits and the drip tip gets too hot for me. Also, the RDA deck is very restrictive on airflow, probably half the airflow of the OCC coils. Kayfun lovers will probably appreciate that but I found it too tight a draw to be enjoyable for me.
You might want to try the Subtank mini. Kanger made some significant changes based on the feedback from the 25mm tank. They used a wide open slot for the largest airflow setting and it feels (and looks) like the Atlantis now. The build deck also has the same airflow and is quite good, easily doubling the airflow of the 25mm tank build deck. A couple of other noticeable changes on the mini is a deeper throat in the top cap so standard drip tips now sit flush rather than sticking up a bit like the 25mm Subtank and no more tiny spring loaded pin for the 510 connection. It now has a good size solid pin for better connection. You don't have to change the top cap to put in the build deck, and don't have to drain the juice in the tank. The top oring has been beefed up to hold the glass better so it won't come loose easily when filling so you don't risk spilling juice for the glass coming loose. Overall the Subtank mini is clearly a better choice as a tank since they fixed problems people noticed on the larger tank. This is especially true with the build deck that now has as good an airflow as the OCC coil (which has much better airflow than the 25mm due to large slotted opening). Not a bad tank at all really. But I agree the 25mm tank left a bit to be desired. All this being said, the construction of the OCC coils and tank mean this will still vape best at 20 to 25watts as far as I'm concerned. But don't let that throw you, it still creates a lot of vapor and the taste is great. Don't let the lower wattage concern you, this is not an Atlantis or Billow that needs the higher wattage to perform well, because it really doesn't.