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.

Highest annual profits, takes it easily.

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

https://ourworldindata.org/technology-adoption

I think the point is that "TV" is a widely varied set of products from many manufacturers, while the iPhone is a product (line) from one company.

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