I've done several tests with a NRF24L01 (standard version and PA+LNA version) in a flat with a lot of wifi access point around and in a country house with a 4G antenna near.
In my country house where i need an important range between sensors and gateway, the best choice is the channel 93 at 250kbps. The channels under 85 are perturbed by local wifi transmission (wifi channel 13 go up to 2,484GHz, which correspond to NRF channel 85) and the channel superior to 101 (2,5GHz) are perturbed by the nearby 4G antenna.
In my flat, because of the very important wifi trafic, the channel 93 is also the best choice but the throughput of 2Mbps gives very best results (no transmission errors at all) than 1Mbps or even 250kbps. This is probably du to a different modulation scheme and a shorter frame duration.