It's not the bigger hashrate chain, its the more difficult one at one and only one moment of time.
so, we need to set up the moment first. If any pool has mined KGCs alone, it's more than obvious that his chain will have the biggest hashrate.

I just told that if (for example 1 hour after the split):
the first chain has found 3 blocks at 10k diff, and the second has found 2 blocks at 16k diff, the winner should be the second one.