[Update #2]: Unfortunately, it looks like the ability to select your preferred card style will not be coming after all. I apologize for any confusion I may have caused. On the positive side, there's a decent chance Wizards of the Coast will add this at some point in the not too distant future as it's a often requested feature and the system for favoriting cards is already implemented.
[Update]: MTG Arena is getting a sizable Lord of The Rings themed expansion on June 20th.
It took nearly two years for us to get here, but I'm happy to say that MTG Arena has now finally added the ability to select your favorite basic lands. All you have to do is choose whichever land art you want as your default in the Collection screen, after which every new deck you make will automatically be filled out with your fanciest lands instead of simply the newest ones.
The system has also been extended to work with card styles, though unfortunately this part of it is a bit buggy right now. Wizards of the Coast is already working on fixing the problem, however, so once the update goes live you'll be able to choose your preferred card printings and styles so you'll never have to manually edit your cosmetics ever again!
Besides the much-needed quality-of-life improvements, the update has also brought with it the Alchemy: Phyrexia mini-set. Much like the previous expansions, Alchemy: Phyrexia comes with 30 entirely new cards to mess around with, most of which have been designed to complement the cards, ideas and playstyles introduced in the main Phyrexia: All Will Be One set.
You can check out the full list of new additions, all neatly sorted by color, over at the official card gallery. Pretty much all of them are usable cards, whether this be in Alchemy or Historic/Historic Brawl, so the set's definitely worth checking out if you're a fan of either format.
The final thing worth mentioning is that Shadow Over Innistrad Remastered will be launching onto MTG Arena on March 21st with 302 'new' cards, as well as 81 extra cards that will even include some classics from the original Innistrad! I'd love to tell you more, but I'm afraid that's pretty much it for the time being. Once the full list of cards becomes available, or Wizards of the Coast announces some other major expansion, I'll make sure to let you know.
Until then, have fun brewing up new decks!