The one reason I have heard for a preference is the engine (specifically the bearings). If you leave a model long term unused one way was preferable . . . but I don't recall which. I try to fly even my least used models at least two outings annually and horizontal has worked for me.

Iwill say the best way for youis likely the method with the lesser chance of stepping on, falling against or dropping something on the model. Ihang the wings in cradles up in or near the rafters - just to prevent collateraldamage.

Two14" lengths of 2 x 4 with a 1" hole at the lower end, screwed intro afloor joist,and 32" of PVC (with foam covering)passed through and sticking out equallyeach sidehorizontally holds two large wings.