Dan, this question has been asked and answered many times on this and other frame building forums. It can be good to refresh and perhaps improve our answers to these basic questions because there can new information and maybe a different way of saying something can make the concept clearer. You can benefit from past answers by using the search feature.
I’m a big promoter of using propane with an oxygen concentrator for reasons of convenience, cost and safety. I can use either fuel without thinking about it but the advantages for propane are big if you get the right equipment. If you are curious about those reasons use the search feature with my name where I write about this in detail various places. I got started using propane in Ukraine where we do a charity bicycle project. It is a place I organized for my frame building students to make basic frames for practice after they finish my 3 week class. They get valuable experience and others benefit from their work so it is a real win win.
While I like most of the aircraft style of torch handles, I personally prefer the Uniweld 71. I combine it with a Victor UN-J mixer/elbow (that is specifically for propane) and use Victor TEN tips (also made for propane). These tips have a recessed end to help keep the flame attached. However the best tips for propane are multi-port tips made by TM Technologies (where it is a good place to get most of your equipment) for the Meco Midget torch handle. They provide a more stable flame. Paige also makes multi-port propane specific tips with Meco threading.
To get my Uniweld 71 torch handle with a Victor UN-j mixer elbow to work with Meco multi-port tips, I have to get an adaptor from TM. I braze this onto a UN-J with a bronze sleeve (made by Hillman sold at most hardware stores) as a connector between the 2. I need to drill out half of one end to 5/16th to fit over the UN-J. The adaptor is 1/4” in diameter.