10S-5P vs 12S-4P? You have enough cells for a 13S-4P, I like that better if this is for an ebike. More S means faster motor speed, but it depends on your riding style. Sometimes slower is better. I think range is about the same though.
Having run both 10S and 13S on the same ebikes, I think the response feels a bit better on the 13S vs 10S when both are almost used up. The 13S will be down to 42V and while it will not accelerate anything like a fresh 10S at 42V, I think it is still more lively than when the 10S is down to 30V.