I like the physical tamagotchis better, because when I tried the app, it was quite boring and I couldn't control the clock, so it constantly got sick/died while I was sleeping. D:
If by "app" you mean "computer programs" then I have to say that both have their merits. My biggest problem is that my computer is a desktop. Tamagotchi CD-ROM at least has a daycare center of sorts... Not sure how this Tamagotchi Simulator program works. But if I were to go on a trip or whatever, I'd probably come back to find them dead. lol
Haven't bothered with the Tamagotchi app on android. I don't do games on my phone, plus I heard it's unsupported and growing buggy.
Looking forward to getting a physical one that I can take places, though. Should be arriving somewhere around the 16th.
Definitely real tamagotchi as nowadays smartphone display is way too big for tamagotchi to fit in, even Sony Xperia Z5 Compact is still too big for it.