Pork, was the first time I ever attempted to make sausage, so I can't really recommend any favorite seasonings.
Was pretty simple, bought a pork shoulder / butt at costco, very good price, wasn't that much at all, ground it up and used 3 recipes I found online for seasonings. Made 3 different types of sausages, used a kitchen aid attachment for it with sausage casings, probably only took an hour to case all of them (a lot, froze about 90%).
Used my first batch in spaghetti, was very pleased with it, and then I used my 2nd batch for some jambalaya, and now I tried some of the "random use w/e you want" sausage for pizza.
Overall I'm very pleased, saved a lot of money doing it but didn't really care about that, I did it because I wanted to try it out and I had a lot of fun doing it.