Where you are a modulating furnace would probably be better. I put in both depending on the house, the less sealed and less efficient a house is the more a modulating furnace will help because the heat load is always ever changing and never holding the heat in.
If it is a really tight insulated house then a two stage furnace should be fine because the house will hold its heat in and it doesn't need constant adjusting that a modulating furnace will. In the tight house the furnace will mostly run in 1st stage and then run in 2nd stage when the house needs to heat up or doors/windows get opened.
As for the sizes, most manufacturers only make 60K BTU as their smallest size in high efficiency furnaces because of the modulation and staging capacities.