Great topic! I'm curious about other people's experiences are as well.
Which version do you prefer personally?
It depends. I read on the PC, so horizontal format is nice for me and it's the format I'm use to after years of reading printed comics. However, vertical comics done right are quite brilliant as well.
Which got more views, subscribers and overall popularity?
My vertical format series is currently more popular (most subscriber, views, etc.), however, I promote that version more. My Oops website, posts a new horizontal page every Saturday, and my Tapastic series (both vertical and horizontal formats) post the same page on Wednesdays. So I don't annoy my followers by sharing a link to the same horizontal page they just saw on the website a few days before, I post links to the vertically format Tapastic page so it's something new and different to check out. I think my vertical format comic is more popular, because I focus more attention on my vertical format comic series than I do the horizontal format Tapastic series.
Did you have some interesting experience with either of the format?
Hmmm, interesting how?
Why did you choose both formats?
I do both because my pages are originally created in horizontal format and Tapastic really encourages creators to create in vertical format. I vertically format my pages for Tapastic to conform to their mobile optimization and I post the original horizontal pages, because they're already done and some reader prefer the horizontal of the vertical.
Oops Comic Adventure Vertical Format
Oops Comic Adventure Horizontal Format