When I travel on a budget (which is usually, lol), I stay at Pop. It is typically slightly over the cost of the All Star resorts, but my rationalization for paying the extra is that Pop does not share a bus line, while All Stars shares between Movies, Music, and Sports. I don't mind paying a little extra a night if it means that I get to my destination immediately via the bus, especially since it far outweighs the expense of renting a car. However, I have also stayed at all three All Star resorts and even with the bus sharing, they aren't terrible places to stay.
If you are planning on spending most of your time in the parks, and not at your room/hotel pool, etc., I would not pay the extra for a moderate if you are on a strict budget.