To be honest, I am not completely sure. This is because I will be traveling to so many different countries and regions of the world that I will be taking an abundance different of types of travel. I decided the easiest way to explain my general plan is break it down by continent.
South America: The subways in Santiago were surprisingly manageable last time I was there, and while in the major cities I plan on using the subway, to go between countries I will most likely be taking buses and ferries. (Antarctica is still my dream destination, and so to get there if I find a way I will be hiding out in Ushuaia and waiting for cruise to Antarctica, or bussing up to the north of Argentina.)
Iceland (not its own continent but its own special case): The weather in March is going to be frigid and wintering, and so my original intention of hiking around and buying the hiking bus pass which will pick you up and drop you off in major cities and trails heads, seems to be debunked. Most sites online recomend highhiking or renting a car which are both options I am looking into. (Mom and Dad no matter what happens I will be very safe, and won't hitch hike alone).
Middle East (another special case): Agian this is not its own continent, but I felt it could be its own category for transportation. My plans are still up in the air for where/when I will be here, and as those plans are solidified, I will have a better idea of how I will be getting around.
Africa: I will only be getting around via cabs or one tour bus/ renting a 4 x 4 for the dessert outside Morocco, hoping to spend a night sleeping outside in the Sahara Desert.
Asia: Here I will be backpacking, and will most likely fly from Vietnam or Thailand to the Philipines. On my way home from Asia I am contemplating boarding a freighter instead of flying home. It would allow me to not only see a different side of travel (the commercial ports) but also take some time to slow down and be by myself. The freighter would leave from China, visiting two cities there and one port in Tokyo before heading to Canada and then Seattle. The whole trip is going to be six months of always exploring and nonstop activities/adventures; I think being able to just hang out on a ship for 10-15 days could be nice. It'll give me time to keep up on the posts that I haven't finished as well reflect on my crazy little adventure.
Oceania: In Australia and potentially New Zealand I will be traveling by bus, potentially again renting a car, depending on who is with me to help pay for it and gas.