I know I have (so has the world) been picking on Google issues recently, but Yahoo! has their share of problems. A WebmasterWorld thread named Spamming Blogs for Top Yahoo Rankings shows that certain spam tactics are working fairly well on Yahoo! also.
Honestly, right now, there is not one engine that I am particularly in love with.
I always had a fall back. For example, Google is going through an update but Yahoo! recently did an update and the results look nice, I would use Yahoo!. Or Yahoo! stunk but Google was solid. MSN, well, that is MSN. Ask.com is just always a bit too slow to update but they do have features that encouraged me to make them my home page. But now what? Google, Yahoo and MSN all pretty much are not doing too well. Sad...
Forum discussion at WebmasterWorld.