Once you reach OKC, there are two options. I-40 to I-25 at Albuquerque, tthen south to I-10, or I-35 to I-820 in Ft Worth, west to I-20 to I-10. Not a significant difference in distance. I would just watch the weather forecast closely, chose your route accordingly, and be prepared to have to stop for a day or two if a winter storm is approaching. It is possible for there to be a storm on I-40 and not on I-20, and vice versa. I would tend toward the I-40/I-25 to avoid Ft Worth and El Paso. But weather forecasts would determine that.