Easier to get to Oviedo vs Madrid from Leon?

Asturias (Oviedo) Airport OVD
http://www.aena.es/csee/Satellite/Aeropuerto-Asturias/en/

ALSA has buses every two hours from Leon to Asturias Airport (entered so) usually involving a transfer at Oviedo. Time is 3 - 4 hours depending on schedule.

ALSA from Leon to Madrid Airport takes 4 - 5 hours. There is frequent service to Madrid (and usually less than 4 hours) but not all buses go to airport. You'd still have to take the Metro or Cercanias from Estacion Sur or Metro from Moncloa to the Airport.

There is frequent Renfe train service from Leon to Oviedo, however Oviedo is quite a distance from Asturias Airport. You would still need to catch the bus in Oviedo.

Renfe time to travel from Leon to Madrid is 3 - 4 hours. You'd still need to get from train station to Airport using Cercanias or Metro.

I'd say the deciding factor would be cost and convenience of the flight.

Personally I would stick with your Oviedo plan. Several trains and more frequent ALSA buses daily from Leon to Oviedo. A fairly short and inexpensive journey. Also Oviedo is a very pleasant town and the fabada and cider are well worth sampling.

Hi Bill, both are good options. However, it would be worth taking some time to see how the bus and train times line up with with your potential flight departure times.

I looked at both options recently when deciding on our travel arrangements for the Del Salvador/Primitivo. Travelling to Leon via Madrid rather than Oviedo worked better for us, especially since some of the fast trains between Madrid and Leon take just 2 hours and 15 minutes. But I was also influenced by the fact that we didn't have the option of a direct flight from Ireland to Oviedo.

If you can change your flight without any penalty, Madrid might give you more flexibility - especially if you don't make it all the way to Leon. You can, for example get a train from Sahagun to Madrid.

But to be honest, the difference between the two options isn't really a big deal. As @whariwharangi said, the cost and convenience of the flight is probably the main deciding factor.

Buen Camino!