It's hard to say really. I started my story wanting to make a manga. I want it to be like the Pixiv mangas where you can read it online but be able to make a print run of it. When you look at my story, there are a lot of evidence of this such as consideration for page gutters, imitating release schedules, interactions of panels, and creating anticipation to turn the page. I design my story as manga first and a webtoon second. This will be and always will be my end goal.
I never planned to post on Webtoons or Tapas because I prefer making my story in a book format. I ended up being convinced by my friend to do so, mostly since I was starting from complete zero; I had no following and didn't post my art prior to posting my story. Posting on sites with an audience would be better than striving out on my own. It was a bit rocky start since I struggled to figure out how to convert a manga to a webtoon smoothly and, most importantly, quickly. While I did figure out a semi quick way to do so, I realize my story lost a lot of what made it manga. Vertical comics have a different feel to them and it was hard to do the same without having to heavily edit my story to fit the form. I eventually came to a compromise where I can display it more like a manga, do so in a timely fashion, and fit the vertical format.
In a way, I came to enjoy posting my story on both Webtoons and Tapas. While I continue to make my story like a manga, I am getting the hang of shifting it into a vertical format. It definitely gets more attention on these sites than it does if I made my own site or just post on Pixiv. I would prefer if there was the ability to read it via page viewers but I won't complain about it. It's hard to say where the future takes me. If my story really picks up in terms of popularity, Tapas and/or Webtoons might be main platform with making a print book and site become a second priority. Until then, it is a stepping plateau that I will be around on for quite some time.