Another vote for the Thule bars from me.
The other thing to remember with the Thule bars is that they can be adapted (normally quite cheaply) to fit other cars, so when you sell the Leon the bars are still useful to you.
Not seen the official SEAT bars for the Leon myself, but I know the MK4 Ibiza ones are made by Atera, not Thule as stated above. I don't know for sure that the Leon ones are Atera, but I can't see SEAT having different roof bar suppliers for different cars.
Atera bars are supposed to be very good quality, although they aren't modular like the Thule bars, so you can't transfer them from car to car. The flip side to this is they're slightly cheaper - depends how often you change cars.
Usefully, all the Thule aerobar accessories will fit Atera bars if you decide to go this route - they have some nice options for transporting boards etc.
Finally, I can highly recomend these people - www.roofbox.co.uk
The other thing to remember with the Thule bars is that they can be adapted (normally quite cheaply) to fit other cars, so when you sell the Leon the bars are still useful to you.
Not seen the official SEAT bars for the Leon myself, but I know the MK4 Ibiza ones are made by Atera, not Thule as stated above. I don't know for sure that the Leon ones are Atera, but I can't see SEAT having different roof bar suppliers for different cars.
Atera bars are supposed to be very good quality, although they aren't modular like the Thule bars, so you can't transfer them from car to car. The flip side to this is they're slightly cheaper - depends how often you change cars.
Usefully, all the Thule aerobar accessories will fit Atera bars if you decide to go this route - they have some nice options for transporting boards etc.
Finally, I can highly recomend these people - www.roofbox.co.uk