Interestingly, I have followed panjandrum's lead but I have come up with drastically different results with seemingly the exact same criteria. Some of our figures are WAY off (like, hundreds of thousands of hits google hits off). Are his numbers fictional? Maybe, but I doubt it. Could it be that I am using google.com from Japan? I don't know. After removing the irrelavent took, take, here is what I got:
54,000 for "I eat breakfast
61,300 for "I have breakfast
64,300 for "I ate breakfast
242,000 for "I had breakfast
186,000 for "you eat breakfast
96,000 for "you have breakfast
7,610 for "you ate breakfast
42,000 for "you had breakfast
25,700 for "we eat breakfast
160,000 for "we have breakfast
84,300 for "we ate breakfast
321,000 for "we had breakfast
BTW, I stumbled upon this topic because I teach English in Japan and a Japanese teacher here was under the same impression that they are under in HK, i.e. "eat" is a direct translation to Japanese yet it is hardly used in real English.