Sanyo NCR21700A (a.k.a. Tesla 21700) is now widely seen in China cell market.
Unlike the earlier expensive prices, it is fairly cheap now. We all know the recessed top is simply awful and makes this cell almost useless, so this issue is already resolved by the sellers in two different ways, as shown in the following pictures:
Method 1:
Adding a plate of nickel, by laser. The introduced resistance is fairly small, but the top still looks slightly recessed after wrapping. Capacity can be up to 4900mAh, at 15A load down to 2.5V.
Method 2:
Adding a normal top. This is a good solution, but the introduced resistance is a bit higher, making the measured average capacity lower (~100mAh lower after measuring 10+ samples by me).
That new LiitoKala 21700 5000mAh appears to be a Sanyo NCR21700A processed with method 2.
Although this Tesla 21700 seems quite good in many aspects, you must beware that the ones you buy may be of lower grade. Since last year I have bought many of this cell from several different sellers, and though they looked identical, their performance varied widely, from 4500mAh to 5000mAh, so, be careful.
And the performance of LISHEN LR2170SF also varies, as I stated here.