Oxen will be my choice because work horses will be hard to come by, and the harness etc is quite complex. I have a book on oxen, and if you look you will find quite a lot on the net. Oxen are SLOW.. but this is good if you have no experience.. as you don’t get into trouble so fast.
From experience I can tell you that a milk cow can produce an enormous amount of your food.. and can do this from eating GRASS… which you cannot eat. Milk and cream can become cheese and butter. You can feed chickens on milk ( and dogs and cats).
And your ox is the byproduct of your cow. ( tho you or one of your neighbours will need to keep a bull. If you train up your ox (castrated bull calf) from birth it will be very used to you and being handled by you. It will take a few years before it is big enough to do much. Read the “little House on the Prairie” book “Alanzos Story” he developed a pair of ox.