Telcel is the biggest mobile network in Mexico and that's already enough of a reason to go for it. Since the cope of this company is so wide that it can even reach all sorts of places, from Puerto Vallarta to Acapulco, you're guaranteed great coverage no matter where you are. It's even bigger than the other two huge telecommunications companies in the country, Movistar and AT&T, which are international entities. That alone stands testament to just how popular and massive Telcel is in Mexico. Not to mention, of course, great deals that can fit any budget!
Originally from Spain, Movistar has grown quite a lot in Mexico too! And whole Telcel beats it when it comes to widespread coverage, it does have the upper hand when it comes to offering data. This isn't to say that the other networks are lacking in that department, but ask any local which company gives the best wifi coverage in Mexico and most of them will say it's Movistar. That's because this network offers up to 5G data and can be accessed in many places throughout the country. This means you can still surf the net or stream a movie no matter where you are.
Finally, there's AT&T. Though it's a well-known American network, it has grown in popularity here in Mexico over the years. And right after TelCel, it has the second-widest spread coverage throughout the country. However, arguably its biggest ace is its international roaming services. Not just in the US and Mexico, AT&T can be used practically anywhere if you have the right plan. So even when you already have an AT&T plan from your native country, you can still use it here in Mexico. That alone is a huge plus for many phone users in the country.