That's really impossible to say until you better define the criteria for success. Most profitable? Most units sold? Greatest dominance in its category? Longest reign? Most cultural relevance?

I don't think iPhone will win any single one of them individually. Grouping together some or all of them...maybe, but probably still no. Heck it might not even the most successful mobile phone ever.

I always thought TV was the most quickly adopted product. Not clear from charts:

https://ourworldindata.org/technology-adoption

Maybe the model T can compete? I expect iPhone to have a longer run though.