I tried 5 searches about subjects I knew well. Results: Google 4, Yahoo 1, Bing 0. But in every case I had to look closely at the results to decide which I preferred. None of them returned obviously bad results for any of the queries.
Then I searched for "wriggly wrolly," which I sometimes call my dog. I ended up clicking for Yahoo again, which had all 4 results.
Sure, only two tries, but I was really surprised with how rewarding this experience was. I wish I could use Yahoo but have it look like Google. I'm just so hooked on Google's branding and image, rather than my 90's-based judgments of Yahoo...maybe I can be stronger of that and make the switch...maybe.
One needs to use any of these search engines over a period of time before making a switch, mostly because the improvements are incremental in Bing.