Make it 1 House per Account
Per server. character-shared.
Also, since Personal Housing has to compete with FC Housing...
Permit us to be co-owners of a house with our friends.
EDIT: fair point about the devaluing of Alt's & RP purposes... however this wouldn't be an issue if SE had implemented Instanced Personal Housing instead... perhaps simply make Houses able to be shared between Alt's so fewer people feel the need to buy multiple homes, along with the above suggestion (co-owners). Or cap at 3.