Heretic of The Seventh Circle
D&D merch is, IME, much more ubiquitous, however.It's important to distinguish between popularity and profitability, too. D&D has always struggled with finding a sustainable business model; the game by its nature doesn't require a lot of ongoing investment by players. Meanwhile, Magic is brilliantly engineered to suck money out of wallets (he said, refreshing to see if there were any more New Capenna spoilers up). So at the same level of popularity, M:tG will be far more profitable.
By this point, I would not be at all surprised to learn that D&D had become significantly more popular than Magic, even though Magic likely continues to bring in more money. Hence all the spinoffs and licensing--Wizards is looking for ways to tap the power of that market.
But even ignoring that, D&D books have been selling much much more in 5e than ever before. It is very unlikely, IMO, that the ratio betweeen the two brands is the same as it ever was.