I don't have a tablet or smartphone, and my attempts at reading comics thru internet readers have always disappointed me. My desktop screen just isn't tall enough to show a whole comics page without uncomfortable scrolling around.
I had a subscription to the paper Shonen Jump, which entitled me to a free version of the online Shonen Jump. I've logged onto that maybe twice in the last six months. Instead, I'm buying the collected editions of the few Manga series that I really liked, and I've dropped the others.
There are a few webcomics that I follow semi-regularly, which mostly are formatted to be easy to read on a desktop screen. When they come out with paper versions, I'm often happy to buy them that way, since I still prefer paper over screen.