MTG Arena, a new online version of the game, is in closed beta and I like it quite a lot. If you want to see how Magic is like nowadays, joining when it goes into open beta may be a good idea.
Other than that, my favorite game mode in MTG has always been drafting, and while drafting free to play is probably not possible right now unless you are amazing, you can draft a lot for little money. I have a win rate under 50% and I can play all the drafts I want to for about 20 dollars per month. If I was a better player, it would be even cheaper.