I get distracted too easily when reading manga online, and I don't feel as immersed as when I'm reading it physically . Although I read more online, if I had more money, I would buy more manga. I like collecting them too.
I used to buy a lot of manga back in the day, but unfortunately, I had to choose between spending money on them or on games. So now I pretty much read everything online—especially since there are many titles in my country that don't even have an official release available for purchase.
If the manga has an emotional value to me ,eg.Vampire knights,it has a special place in my heart, I would get the physical manga but other than that online all the way haha I can't say I am a collector
In my case, I prefer the digital version because it's easier to read on my cell phone or laptop while I'm studying, but the biggest problem is that in my home country it's very hard to find physical manga, and even harder to find them in my native language.
Online for convenience and staying up to date, but physical manga for keepsakes! Nothing beats holding a real volume, admiring the cover art on a shelf, and appreciating double-page spreads without seams, though digital is definitely a lifesaver when your room completely runs out of storage space.