dusts off my standard rant on this
There's no "better" format for you comic here on Tapas, both are pretty common and pretty popular. While Tapas itself encourages vertical scrolling, there are plenty of popular comics that are page format. As long as your text is readable and clear on mobile, people tend not to mind.
Certain people will try to tell you certain things can't be done vertical style (no interesting paneling is the most common one) and this is a lie and a lazy cop out of people who don't want to take the time to figure out how to do these things in vertical scrolling so declare it impossible (because no one likes the new style of anything, ever, no matter what the industry).
If you are willing to put in the time, you can do creative things in either style. If your story and art are solid, your popularity won't be hugely effected either way (at least on Tapas).
And personally, I don't mind either way to read, but prefer a vertical scroll for drawing because I like doing big scrolling vertical scenes like of my giant robots to give a sense of massive scale.