What to buy after foundation?

Hi all,

I bought the foundations set for me and my buddy for christmas. We love it, but now we have played alot and I wonder what to get next.

I have played mtg alot when I was younger and we only played what is now called standard. I stopped playing way before commander (Atleast I think this is what it is called) became the way to play. I used to just buy one or two starter decks and kept adding or swapping with new cards from boosters, whenever I could afford them.

How is it nowadays? Where do I go from foundations? We like the decks so far (I always liked angels) and want to keep playing with new cards or new decks and mix and match with what we have.

Thank you in advance!