Having experimented with both, I can give a definite answer: it depends on what resources you have available.

As already stated, ethanol can be made from any sugar and sugar can be made from any starch (google "spit beer") but getting it pure enough to run a vehicle takes a lot of effort. I worked with a small company once to try and build a solar-heated distillation unit but the flow was never stable enough for a high-purity output. We ended up concentrating it down with a solar still and then had to switch over to a traditional still coupled with azeotroping it with benzene to make a usable fuel. Getting the benzene or something similar would be very difficult in a "made by hand" world.

The guy two doors down from me spent a few years playing with biodiesel fuel for two old Mercedes. Grease/fat/oils can be obtained from both plant and animal sources with medium amounts of effort, methanol is the main product of the destructive distillation of wood (easy to do at home), and sodium hydroxide can be obtained from leaching hard wood ash. One can replace the methanol with ethanol for a slightly inferior product but also easier to make. The trick with biodiesel is getting enough oil to run your truck any distance. There are lots of different oil-press plans on the internet, my favorite involves a welded frame and a hydraulic jack. Squeeze the sunflower seeds, peanuts, or even acorns and watch the oil ooze out...then repeat a bunch more times. Sidenote: the white, waxy coating on the outside of Chinese tallow trees can be made into a good biodiesel. We have TONS of those trees all over Houston.

The actual reaction involved in making biodiesel is even simpler than making alcohol and the "clean-up" of the fuel to make it ready for your vehicle is also easier but somewhat heat and time dependent plus you end up with a lot of waste glycerol and caustic water, both of which currently are difficult to legally dispose.

Conclusion: it depends on what feedstock you have access too. My personal preference is biodiesel because the equipment and raw materials to produce it are easier for ME to obtain. What's easier for you?
-Blast