I am going to buy a box of each of the new set. Can you guys reccomend a third thing to buy? should i get a starter box set? or maybe just another set of the new stuff?

Starter boxes. If history has taught us anything the fixed starter cards are usually tourney worthy if not ban worthy

if I were to choose a third thing to buy, most likely starter decks because that helps with getting uncommons and any starter-exclusive cards... if any still exist.

or buy a box of one of the older sets... like the other sc3 set

Best thing to do is try too see if you can get some of the set 8 starters that FFG recently distributed or wait a few weeks for set 12 they will have starters for that as well.

Starter boxes are great because not only do you get 4x all the exclusives, but also get twice as many commons and uncommons as you would in a booster box, for usually close to the same price. You miss out on pack rares/ultras of course, but if you're relatively new and need cards to work with moreso than trade bait it's well worth it.