That be my recommendation Samsung 40T. Very close to the 30T with initial voltage under load at first but after 1/6 the discharge the voltage stays higher and last longer making the 40T better for the rest of the discharge.
The Sony/Murata US21700VTC6A which is easier to find is much better than the Samsung INR21700-40T, knowing that the first 40T that have been produced and sold (batches of 2Hxx to 2I9x) are versions of preproductions (the Postproductions “finalized” only start from “2IAx” batches and those that follow) are not at the performance listed in their datasheet, it is unfortunately the policy of Samsung that wants this, Murata (formerly Sony) has a different view of things, it does not launch a product to mass sales until it is finalized, so the US21700VTC6A is really keeping its promises, for an average capacity of 4200mAh and 30 Continuous amps (and without exceeding 80 degrees Celsius, which is not the case of the first 40T sold). Another much better cell whose sales have just been launched (here also models “finalized” and not pre-production) Molicel INR-21700-P42A, still for 4200mAh of medium capacity (low load, I grant you ) and 30 amperes continuously well below 80 degrees Celsius (74°C max on mine tested last week).
I checked my Sofirn 21700 batteries and as far as I can tell these seem to be quite okay, with 13.5mOhm AC Ri these are just a good average between Samsung's 40T highdrainer (7.4mOhm AC Ri) and Samsung's 50E lowdrain-, high capacity cell (22mOhm AC Ri). Lately, I discovered that Sofirn puts two different cells underneath the shrink and one of them seems to be Lishen's 2170SA that you can also find as Liitokala 21700 4000mAh or Shockli 21700 4000mAh.
My personal new favorite 21700 cell is the Sanyo NCR21700A 5000mAh 15A (also sold as Vapcell INR21700 5000mAh 15A) that is known to be the "Tesla cell". It's voltage curve looks great, it's AC Ri is only 11mOhms and performs very well in my new Rofis MR30 (boost driver) even when below 3.9V. This is a great battery when it's not about very high currents (> 10A).
I see this vapcell has recessed top +ve nod. Its high capacity cell capable 15a discharge but, may I know what charger do you use to charges those battery?? Seem to me, not all charger would able or fit due to receesed top.
What! I’ve just order Miboxer C4-12… nevermind, glad I didn’t order them. I mention this bcos some of the flashlight brand with built in charger uses 5000mah with 15A, so i went to find out. I think it was sanyo NCR21700 rewrap but not sure.