Formerly known as T-Mobile, Magyar Telekom is the biggest telecommunications company in Hungary. Offering both prepaid and post-paid plans, you have a myriad of options to choose from, each a good deal in of itself. But its real ace in the game is, in fact, it's sheer size, allowing for a bigger scope than its competitors. No matter where you are in Hungary, be it in a Budapest district or in the rural town of Szentendre, you'll still get coverage and good data! Their 2G and 4G LTE networks are killer, though their 3G service leaves a lot to be desired.
Telenor, on the other hand, are what many would recommend to tourists or short-term visitors in Hungary. Why? Because of two major things: low pricing and great customer service. Of course, for the former, it's always better for tourists to spend as little money as possible on relatively trivial things. The less you spend on getting a local SIM card, the better. And with Telenor, for as low as 3,800.00 Ft (only €10.56/$12.69), you can already get a great prepaid deal. As for the latter, great customer service is essential for foreigners who might not be able to speak or understand Hungarian at all.
Vodafone is more of an international mobile telecommunications company than a local one here in Hungary. But it's so popular in this country that there are a lot of locals who've gotten into this network, making it seem like it's local when it's really not. In any case, its international standing is both a pro and con when deciding to get a local SIM card from here. It's a pro because you can also use it anywhere else in Europe, sort of like a Schengen Visa in SIM card form. But the con here is that its scope is not as big in Hungary at large.
Digi, on the other hand, is a super young player in the game here in Hungary. How young? It was launched just last 2019. But is age really that much of an issue? Not necessarily. Though its limit in years means the coverage might not be at its full capacity yet, it does mean that Digi's system has probably worked out its kinks and whatnot. Furthermore, since the network is relatively young, you can expect more affordable prices as well. After all, paying for a SIM card in Hungary shouldn't be your most expensive purchase in the country!
Don't forego getting a local SIM card in Hungary if you're planning to stay here for a period of time. You might realize that living in this country without one might prove to be too much for even you to handle, no matter how experienced you are in traveling.
Instead of paying a lot of money to get into wifi hotspots just so you could use your phone without getting a local SIM card, you could save your money to getting a luxurious home in Hungary.