Quality of results had absolutely nothing to do with the decision, Google and Microsoft bid on the right to be the search engine. Since Microsoft had already been on the platform they may have seen poor or negative ROI from the deal. Google outbid them with a $3 Billion deal, simple as that.

Simple searches you would do from your phone would be/are neck and neck between Google and Bing, where they diverge a bit are more complex/technical queries.

Last part: deal breaker for me. I can't speak for others, but I am going to assume many feel the same. I couldn't stand looking at Yahoo search results. I switched back to Google after Firefox made Yahoo the prefer choicd (the deal with Yahoo)

Yahoo results aren't the same as Bing's; it is merely powered by it, Yahoo still has some control over results and how it uses Bing's service.

It is essentially the same result when the underlying engine is Bing, even though Yahoo can choose how to use the engine.

I’m not as convinced about the quality of text search for bing vs google. I’ve found the former to be inferior in terms of SEO gaming.

That said, it doesn’t use AMP (not relevant here) and its map and images offering is excellent.