AI'm just a hobby baker hoping to take it to the next level . Just wondered what everyone uses to cover with fondant . Is a sponge cake strong enough to be covered and decorated ? Or does a Madeira cake work better . So far I've just used Madeira but sometimes they come out a bit dry . Last one I done was dry on top and crispy and dry on the side a little . I didn't have the butter as soft as I usually do so wondered if that made it crispy on top .

I normally use a Madeira, as I like the flavour better.  I would think sponge cake should be fine too, though. 

With regards to the dry and crispy cake, are you sure you're not over-baking it?  Maybe turn the temp down slightly and check it a bit earlier.  I find my Madeiras are lovely and moist.