I play on a laptop, it’s more comfortable for me, the screen is large, the interface of the poker room on a laptop is more convenient. pokerstars almost stopped using the smartphone version due to the crappy design and options interface
it all depends on the situation, the day and the number of tournaments. it happens that good tournaments take place at the same time in different rooms, then I play from my laptop.... if I'm very tired and just want to play, then I can load one table on my phone... so if I'm going to the subway, then I'm playing with a smartphone))
At the present time I play in the different kinds of Poker, using only my favorite personal computer, sitting before big monitor on the soft couch...
This is more comfortable for Me, and Main, I think, is more useful for my Health! That's it!
I think it's best to play on a laptop. You can multitable and use HUDs which you couldn't on a phone. But nowadays I play free rolls on my phone a lot, as it's more convenient.
If I'm at home, I play on my PC. If I'm at work and have free time, I can play from my phone, although it's generally quite inconvenient. The best option is to play at home on a large monitor while lying on the couch.