When staying at FW, we normally drive to all the parks except MK. The drive to the parks is actually really easy for me, but I am usually really good with maps and road signs. It is really nice to just walk out and get into the car from our cabin and get where we are going without waiting. It made the return just as nice.
I do not really mind the buses, but I just get annoyed with them at some point during a trip, usually due to a longer than normal wait or too crowded of a bus.
Since you mentioned the HA cabins, I thought I would point out some items to know about if you use a mobility device on WDW buses. Only 2-3 devices can be loaded per bus and they are loaded first and unloaded last for safety reasons. This means that if you show up and there are already 2 devices, you might have to wait for an additional bus. If they have already started loading as you arrive, you might have to wait for an additional bus.
If you do not have a mobility device, but have someone that cannot stand on a moving bus, you also need to watch as they load to make sure that there will be somewhere for that person to sit. Not everyone can or will give up a seat if it is standing room only already. If there is not a spot for that person to sit, you might want to wait for the next bus.