P42A is good cell, so if you insist on this particular category 21700, 4Ah, 5C continuous cell, then the only widely available competitor from brand cells is Samsung 40T series where older 40T is slightly worse than P42A in all technical parameters, but the new model 40T3 is expected to be slightly better.
The question is if you really need 5C continuous cell as from 14s3p battery with 1000W motor it is about 8A per cell and it will be only peak value. I think almost all 21700, 5Ah, high energy cells will work in your application well with benefit of slightly better range and significantly lower price.